seven-transmembrane G protein-coupled receptor superfamily; This hierarchical evolutionary model represents the seven-transmembrane (7TM) receptors, often referred to as G protein-coupled receptors (GPCRs), which transmit physiological signals from the outside of the cell to the inside via G proteins. GPCRs constitute the largest known superfamily of transmembrane receptors across the three kingdoms of life that respond to a wide variety of extracellular stimuli including peptides, lipids, neurotransmitters, amino acids, hormones, and sensory stimuli such as light, smell and taste. All GPCRs share a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes. However, some 7TM receptors, such as the type 1 microbial rhodopsins, do not activate G proteins. Based on sequence similarity, GPCRs can be divided into six major classes: class A (the rhodopsin-like family), class B (the Methuselah-like, adhesion and secretin-like receptor family), class C (the metabotropic glutamate receptor family), class D (the fungal mating pheromone receptors), class E (the cAMP receptor family), and class F (the frizzled/smoothened receptor family). Nearly 800 human GPCR genes have been identified and are involved essentially in all major physiological processes. Approximately 40% of clinically marketed drugs mediate their effects through modulation of GPCR function for the treatment of a variety of human diseases including bacterial infections.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  868 AGAPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 947
Cdd:cd15988      1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  948 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1027
Cdd:cd15988     81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1028 LVNMLIGIIVFNKLMARDGVSDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1074
Cdd:cd15988    161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                          250       260       270       280       290
                   ....*....|....*....|....*....|....*....|....*....|.
gi 1783384314 1075 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1125
Cdd:cd15988    241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

GPCR-Autoproteolysis INducing (GAIN) domain; The GAIN a domain of alpha-helices and beta-strands that is found in cell-adhesion GPCRs and precedes the GPS motif where the autoproteolysis occurs, family, pfam01825. The full GAIN domain, comprises the GPS and the GAIN, in cell-adhesion GPCRs, and is the functional unit for autoproteolysis. The GPS motif at the end of the GAIN domain is an ancient domain that exists in primitive ancestor organizms, and the full GAIN + GPS is conserved in all cell-adhesion GPCRs and all PKD1-related proteins.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  550 GMSQVVRSLQELLARRTYYSGDLLFSVDILRNVTDTFKRATYVPSADDVQRFFQVVSFMVDSENKDKWDDAQQVSPGSVH 629
Cdd:pfam16489    1 GAKELARELRNATRHGPLYGGDVLTAVELLSQLFDLLATQDATLSNAFLENFVQTVSNLLDPENRESWEDLQQTERGTAA 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  630 --LLRVVEDFIHLVGDALKAFQSSLIVTDNLVISIQRE--PISAVSSDITFPMRGRRGmkdwvrHSEDRLFLPKEVLSLS 705
Cdd:pfam16489   81 tkLLRTLEEYALLLAQNMKYLTPFTIVTPNIVLSVDRLdtHNFKGARFPRFPMKGERP------KDEDSVKLPPKAFKPP 154

G-protein-coupled receptor proteolytic site domain; Present in latrophilin/CL-1, sea urchin REJ and polycystin.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|....
gi 1783384314   809 TDPHCASWDYSRadtnsGDWNTESCQTLETQAAHTRCQCQHLSTFAVLAQPPKD 862
Cdd:smart00303    1 FNPICVFWDESS-----GEWSTRGCELLETNGTHTTCSCNHLTTFAVLMDVPPI 49

Thrombospondin type 1 repeats; Type 1 repeats in thrombospondin-1 bind and activate TGF-beta.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|...
gi 1783384314   358 WLEWGPWGPCSSSCANGTQQRSRKCSVAGPAW--ATCAGALTDTRECSNLDCP 408
Cdd:smart00209    1 WSEWSEWSPCSVTCGGGVQTRTRSCCSPPPQNggGPCTGEDVETRACNEQPCP 53

brain-specific angiogenesis inhibitor 2, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  868 AGAPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 947
Cdd:cd15988      1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  948 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1027
Cdd:cd15988     81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1028 LVNMLIGIIVFNKLMARDGVSDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1074
Cdd:cd15988    161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                          250       260       270       280       290
                   ....*....|....*....|....*....|....*....|....*....|.
gi 1783384314 1075 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1125
Cdd:cd15988    241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

7 transmembrane receptor (Secretin family); This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors (GCPRs). They have been described in many animal species, but not in plants, fungi or prokaryotes. Three distinct sub-families are recognized. Subfamily B1 contains classical hormone receptors, such as receptors for secretin and glucagon, that are all involved in cAMP-mediated signalling pathways. Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin, and brain-specific angiogenesis inhibitors amongst others. Subfamily B3 includes Methuselah and other Drosophila proteins. Other than the typical seven-transmembrane region, characteriztic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  868 AGAPSVPLVIGCAVSCMALLTLLAIYAAFwRFIKSERSIILLNFCLSILASNILILVGQSRVLSKG--------VCTMTA 939
Cdd:pfam00002    1 ALSLKVIYTVGYSLSLVALLLAIAIFLLF-RKLHCTRNYIHLNLFASFILRALLFLVGDAVLFNKQdldhcswvGCKVVA 79

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  940 AFLHFFFLSSFCWVLTEAWQSYLA-VIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTrTKGYGTSSYCWLSLEGGLLYA 1018
Cdd:pfam00002   80 VFLHYFFLANFFWMLVEGLYLYTLlVEVFFSERKYFWWYLLIGWGVPALVVGIWAGVD-PKGYGEDDGCWLSNENGLWWI 158

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1019 FVGPAAVIVLVNMLIGIIVFNKLMARDGVSDKSKKQRAGASLW--SSCVVLPLLALTWMSAVLAMTDRR--SVLFQALFA 1094
Cdd:pfam00002  159 IRGPILLIILVNFIIFINIVRILVQKLRETNMGKSDLKQYRRLakSTLLLLPLLGITWVFGLFAFNPENtlRVVFLYLFL 238

                          250
                   ....*....|
gi 1783384314 1095 VFNSAQGFVI 1104
Cdd:pfam00002  239 ILNSFQGFFV 248

Thrombospondin type 1 repeats; Type 1 repeats in thrombospondin-1 bind and activate TGF-beta.

                            10        20        30        40        50
                    ....*....|....*....|....*....|....*....|....*....|...
gi 1783384314   303 WEEWGSWSLCSRSCGRGSRSRMRTCV--PPQHGGKACEGPELQTKLCSMAACP 353
Cdd:smart00209    1 WSEWSEWSPCSVTCGGGVQTRTRSCCspPPQNGGGPCTGEDVETRACNEQPCP 53

GPCR proteolysis site, GPS, motif; The GPS motif is found in GPCRs, and is the site for auto-proteolysis, so is thus named, GPS. The GPS motif is a conserved sequence of ~40 amino acids containing canonical cysteine and tryptophan residues, and is the most highly conserved part of the domain. In most, if not all, cell-adhesion GPCRs these undergo autoproteolysis in the GPS between a conserved aliphatic residue (usually a leucine) and a threonine, serine, or cysteine residue. In higher eukaryotes this motif is found embedded in the C-terminal beta-stranded part of a GAIN domain - GPCR-Autoproteolysis INducing (GAIN). The GAIN-GPS domain adopts a fold in which the GPS motif, at the C-terminus, forms five beta-strands that are tightly integrated into the overall GAIN domain. The GPS motif, evolutionarily conserved from tetrahymena to mammals, is the only extracellular domain shared by all human cell-adhesion GPCRs and PKD proteins, and is the locus of multiple human disease mutations. The GAIN-GPS domain is both necessary and sufficient functionally for autoproteolysis, suggesting an autoproteolytic mechanism whereby the overall GAIN domain fine-tunes the chemical environment in the GPS to catalyze peptide bond hydrolysis. In the cell-adhesion GPCRs and PKD proteins, the GPS motif is always located at the end of their long N-terminal extracellular regions, immediately before the first transmembrane helix of the respective protein.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*.
gi 1783384314  811 PHCASWDYSraDTNSGDWNTESCQTLETQAAHTRCQCQHLSTFAVL 856
Cdd:pfam01825    1 PQCVFWDFT--NSTTGRWSTEGCTTVSLNDTHTVCSCNHLTSFAVL 44

Spondin-like TSP1 domain; This entry represents a sub-type of TSP1 domains that have an alternative disulphide binding pattern compared to the canonical TSP1 domain.

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 1783384314  305 EWGSWSLCSRSCGRGSRSRMRT-CVPPQHGGKACeGPELQTKLCSMAAC 352
Cdd:pfam19028    5 EWSEWSECSVTCGGGVQTRTRTvIVEPQNGGRPC-PELLERRPCNLPPC 52

Domain present in hormone receptors;

                            10        20        30        40        50        60        70
                    ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 1783384314   467 HEMCRDEYVMLMTWKRAAAGEIIYNKCPPNASG-----SASRRCLLSAQgvayWGL--PSFARCISHEYRYL 531
Cdd:smart00008    2 DLGCPATWDGIICWPQTPAGQLVEVPCPKYFSGfsyktGASRNCTENGG----WSPpfPNYSNCTSNDYEEL 69

Thrombospondin type 1 domain;

                           10        20        30        40
                   ....*....|....*....|....*....|....*....|....*....
gi 1783384314  415 GPWNAWSLCSKTCDTGWQRRFRMCQASGTQGYPCEGTGEEVKPCSEKRC 463
Cdd:pfam00090    1 SPWSPWSPCSVTCGKGIQVRQRTCKSPFPGGEPCTGDDIETQACKMDKC 49

Hormone receptor domain; This extracellular domain contains four conserved cysteines that probably for disulphide bridges. The domain is found in a variety of hormone receptors. It may be a ligand binding domain.

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 1783384314  467 HEMCRDEYVMLMTWKRAAAGEIIYNKCPPNAS-----GSASRRCLLSAQgvayWGLPS---FARCISH 526
Cdd:pfam02793    1 GLGCPRTWDGILCWPRTPAGETVEVPCPDYFSgfdprGNASRNCTEDGT----WSEHPpsnYSNCTSN 64

brain-specific angiogenesis inhibitor 2, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  868 AGAPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFL 947
Cdd:cd15988      1 TGSPSVPLMIGCAVSCMALLILLAIYAAFWRFIRSERSIILLNFCLSILASNILILVGQSQTLSKGVCTMTAAFLHFFFL 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  948 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIV 1027
Cdd:cd15988     81 SSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTASYCWLSLEGGLLYAFVGPAAVIV 160

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1028 LVNMLIGIIVFNKLMARDGVSDKSKKQRAG---------------------------------ASLWSSCVVLPLLALTW 1074
Cdd:cd15988    161 LVNMLIGIIVFNKLMSRDGISDKSKKQRAGseaepcsslllkcskcgvvssaamssatassamASLWSSCVVLPLLALTW 240

                          250       260       270       280       290
                   ....*....|....*....|....*....|....*....|....*....|.
gi 1783384314 1075 MSAVLAMTDRRSVLFQALFAVFNSAQGFVITAVHCFLRREVQDVVKCQMGV 1125
Cdd:cd15988    241 MSAVLAMTDRRSILFQVLFAVFNSVQGFVIITVHCFLRREVQDVVKCQMGG 291

brain-specific angiogenesis inhibitor 1, a group VII adhesion GPCR, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Brain-specific angiogenesis inhibitors (BAI1-3) constitute the group VII of cell-adhesion receptors that have been implicated in vascularization of glioblastomas. They belong to the B2 subfamily of class B GPCRs, are predominantly expressed in the brain, and are only present in vertebrates. Three BAIs, like all adhesion receptors, are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. For example, BAI1 N-terminus contain an integrin-binding RGD (Arg-Gly-Asp) motif in addition to five thrombospondin type 1 repeats (TSRs), which are known to regulate the anti-angiogenic activity of thrombospondin-1, whereas BAI2 and BAI3 have four TSRs, but do not possess RGD motifs. The TSRs are functionally involved in cell attachment, activation of latent TGF-beta, inhibition of angiogenesis and endothelial cell migration. The TSRs of BAI1 mediates direct binding to phosphatidylserine, which enables both recognition and internalization of apoptotic cells by phagocytes. Thus, BAI1 functions as a phosphatidylserine receptor that forms a trimeric complex with ELMO and Dock180, leading to activation of Rac-GTPase which promotes the binding and phagocytosis of apoptotic cells. BAI3 can also interact with the ELMO-Dock180 complex to activate the Rac pathway and can also bind to secreted C1ql proteins of the C1Q complement family via its N-terminal TSRs. BAI3 and its ligands C1QL1 are highly expressed during synaptogenesis and are involved in synapse specificity. Moreover, BAI2 acts as a transcription repressor to regulate vascular endothelial growth factor (VEGF) expression through interaction with GA-binding protein gamma (GABP). The N-terminal extracellular domains of all three BAIs also contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain, which undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif to generate N- and C-terminal fragments (NTF and CTF), a putative hormone-binding domain (HBD), and multiple N-glycosylation sites. The C-terminus of each BAI subtype ends with a conserved Gln-Thr-Glu-Val (QTEV) motif known to interact with PDZ domain-containing proteins, but only BAI1 possesses a proline-rich region, which may be involved in protein-protein interactions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  865 LELAGAPSVPLVIGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHF 944
Cdd:cd15990      1 MEKALLPSVTLIVGCGVSSLTLLLLIIIYVSVWRYIRSERSVILINFCLSIISSNALILIGQTQTRNKVVCTLVAAFLHF 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  945 FFLSSFCWVLTEAWQSYLAVIGRMRTRLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAA 1024
Cdd:cd15990     81 FFLSSFCWVLTEAWQSYMAVTGRLRNRIIRKRFLCLGWGLPALVVAISVGFTKAKGYGTVNYCWLSLEGGLLYAFVGPAA 160

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1025 VIVLVNMLIGIIVFNKLMARDGVSDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLFQALFAVFNSAQGFVI 1104
Cdd:cd15990    161 AVVLVNMVIGILVFNKLVSKDGITDKKLKERAGASLWSSCVVLPLLALTWMSAVLAITDRRSALFQILFAVFDSLEGFVI 240

                          250       260
                   ....*....|....*....|....*.
gi 1783384314 1105 TAVHCFLRREVQDVVKCQMgVCRADE 1130
Cdd:cd15990    241 VMVHCILRREVQDAVKCRV-VDRQEE 265

Adhesion GPCR B N-terminal region; This region is found at the N-terminus of various adhesion G-protein coupled receptor B proteins. This region contains 10 cysteine residues that probably form disulphide bonds.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314   26 SACSALASGVLYGAFSLQDLFPTIASGCSWTLENPDPTKYSLYLRFNRQEQVCTHFAPRLLPLDHYLVNFTclrpgpeea 105
Cdd:pfam19188    1 DPCSTLVQGVLYGSFSLRDLFPTNASGCSWTLENPDPTKYTLYLKFTKPTQSCLPFSPRLLQFDHYLENTT--------- 71

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  106 taraESEVGRPeeeeeeaaAAASGLELCGGSGPFTFLHFDKNFVQLCLSAEPSEAPRLLAPAALAFRFVEVLLINNNNSS 185
Cdd:pfam19188   72 ----RTYLGRE--------SFDEVVELCDASSPFSFLEFDKNFVQLCLLAEPRGDPESVVPGPSGDFKVEVLVINNENPS 139

                          170       180       190
                   ....*....|....*....|....*....|....*...
gi 1783384314  186 QFTCGVLCRWSEECGRAA--GRACGFAQPGCSCPGEAG 221
Cdd:pfam19188  140 QFTCGVLCRWLEECLSAStsSRPCGIMQTPCICPGTVP 177

adhesion receptors, subfamily B2 of the class B family of seven-transmembrane G protein-coupled receptors; The B2 subfamily of class B GPCRs consists of cell-adhesion receptors with 33 members in humans and vertebrates. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing a variety of structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, linked to a class B seven-transmembrane domain. These include, for example, EGF (epidermal growth factor)-like domains in CD97, Celsr1 (cadherin family member), Celsr2, Celsr3, EMR1 (EGF-module-containing mucin-like hormone receptor-like 1), EMR2, EMR3, and Flamingo; two laminin A G-type repeats and nine cadherin domains in Flamingo and its human orthologs Celsr1, Celsr2 and Celsr3; olfactomedin-like domains in the latrotoxin receptors; and five or four thrombospondin type 1 repeats in BAI1 (brain-specific angiogenesis inhibitor 1), BAI2 and BAI3. Furthermore, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  877 IGCAVSCMALLTLLAIYAAFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCWVLTE 956
Cdd:cd15040     10 IGCGLSLLGLLLTIITYILFRKLRKRKPTKILLNLCLALLLANLLFLFGINSTDNPVLCTAVAALLHYFLLASFMWMLVE 89

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  957 AWQSYLAVIGRMRT--RLVRKRFLCLGWGLPALVVAVSVGFTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIVLVNMLIG 1034
Cdd:cd15040     90 ALLLYLRLVKVFGTypRHFILKYALIGWGLPLIIVIITLAVDPDSYGNSSGYCWLSNGNGLYYAFLGPVLLIILVNLVIF 169

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1035 IIVFNKLMARDGVSDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVlFQALFAVFNSAQGFVITAVHCFLRRE 1114
Cdd:cd15040    170 VLVLRKLLRLSAKRNKKKRKKTKAQLRAAVSLFFLLGLTWIFGILAIFGARVV-FQYLFAIFNSLQGFFIFIFHCLRNKE 248

                   ...
gi 1783384314 1115 VQD 1117
Cdd:cd15040    249 VRK 251

class B family of seven-transmembrane G protein-coupled receptors; The class B of seven-transmembrane GPCRs is classified into three major subfamilies: subfamily B1 (secretin-like receptor family), B2 (adhesion family), and B3 (Methuselah-like family). The class B receptors have been identified in all the vertebrates, from fishes to mammals, as well as invertebrates including Caenorhabditis elegans and Drosophila melanogaster, but are not present in plants, fungi or prokaryotes. The B1 subfamily comprises receptors for polypeptide hormones of 27-141 amino-acid residues such as secretin, glucagon, glucagon-like peptide (GLP), calcitonin gene-related peptide, parathyroid hormone (PTH), and corticotropin-releasing factor. These receptors contain the large N-terminal extracellular domain (ECD), which plays a critical role in hormone recognition by binding to the C-terminal portion of the peptide. On the other hand, the N-terminal segment of the hormone induces receptor activation by interacting with the receptor transmembrane domains and connecting extracellular loops, triggering intracellular signaling pathways. All members of the subfamily B1 receptors preferentially couple to G proteins of G(s) family, which positively stimulate adenylate cyclase, leading to increased intracellular cAMP formation and calcium influx. The subfamily B2 consists of cell-adhesion receptors with 33 members in humans and vertebrates. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing a variety of structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, linked to a class B seven-transmembrane domain. These include, for example, EGF (epidermal growth factor)-like domains in CD97, Celsr1 (cadherin family member), Celsr2, Celsr3, EMR1 (EGF-module-containing mucin-like hormone receptor-like 1), EMR2, EMR3, and Flamingo; two laminin A G-type repeats and nine cadherin domains in Flamingo and its human orthologs Celsr1, Celsr2 and Celsr3; olfactomedin-like domains in the latrotoxin receptors; and five or four thrombospondin type 1 repeats in BAI1 (brain-specific angiogenesis inhibitor 1), BAI2 and BAI3. Almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. Furthermore, the subfamily B3 includes Methuselah (Mth) protein, which was originally identified in Drosophila as a GPCR affecting stress resistance and aging, and its closely related proteins.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  876 VIGCAVSCMALLTLLAIYAAFWRFIKSeRSIILLNFCLSILASNILILVGQSRVLSKG--VCTMTAAFLHFFFLSSFCWV 953
Cdd:cd13952      9 YIGCSLSLVGLLLTIITYLLFPKLRNL-RGKILINLCLSLLLAQLLFLIGQLLTSSDRpvLCKALAILLHYFLLASFFWM 87

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  954 LTEAWQSYLAVIGRMRTRLvRKRFL---CLGWGLPALVVAVSVGFTRT----KGYGTSSYCWLSLEGGLLYAFVGPAAVI 1026
Cdd:cd13952     88 LVEAFDLYRTFVKVFGSSE-RRRFLkysLYGWGLPLLIVIITAIVDFSlygpSPGYGGEYCWLSNGNALLWAFYGPVLLI 166

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1027 VLVNMLIGIIVFNKLMARDGVSDK-SKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLFQALFAVFNSAQGFVIT 1105
Cdd:cd13952    167 LLVNLVFFILTVRILLRKLRETPKqSERKSDRKQLRAYLKLFPLMGLTWIFGILAPFVGGSLVFWYLFDILNSLQGFFIF 246

                          250
                   ....*....|.
gi 1783384314 1106 AVHCFLRREVQ 1116
Cdd:cd13952    247 LIFCLKNKEVR 257

GPCR-Autoproteolysis INducing (GAIN) domain; The GAIN a domain of alpha-helices and beta-strands that is found in cell-adhesion GPCRs and precedes the GPS motif where the autoproteolysis occurs, family, pfam01825. The full GAIN domain, comprises the GPS and the GAIN, in cell-adhesion GPCRs, and is the functional unit for autoproteolysis. The GPS motif at the end of the GAIN domain is an ancient domain that exists in primitive ancestor organizms, and the full GAIN + GPS is conserved in all cell-adhesion GPCRs and all PKD1-related proteins.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  550 GMSQVVRSLQELLARRTYYSGDLLFSVDILRNVTDTFKRATYVPSADDVQRFFQVVSFMVDSENKDKWDDAQQVSPGSVH 629
Cdd:pfam16489    1 GAKELARELRNATRHGPLYGGDVLTAVELLSQLFDLLATQDATLSNAFLENFVQTVSNLLDPENRESWEDLQQTERGTAA 80

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  630 --LLRVVEDFIHLVGDALKAFQSSLIVTDNLVISIQRE--PISAVSSDITFPMRGRRGmkdwvrHSEDRLFLPKEVLSLS 705
Cdd:pfam16489   81 tkLLRTLEEYALLLAQNMKYLTPFTIVTPNIVLSVDRLdtHNFKGARFPRFPMKGERP------KDEDSVKLPPKAFKPP 154

cadherin EGF LAG seven-pass G-type receptors, group IV adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; The group IV adhesion GPCRs include the cadherin EGF LAG seven-pass G-type receptors (CELSRs) and their Drosophila homolog Flamingo (also known as Starry night). These receptors are also classified as that belongs to the EGF-TM7 group of subfamily B2 adhesion GPCRs, because they contain EGF-like domains. Functionally, the group IV receptors act as key regulators of many physiological processes such as endocrine cell differentiation, neuronal migration, dendrite growth, axon, guidance, lymphatic vessel and valve formation, and planar cell polarity (PCP) during embryonic development. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, that are coupled to a class B seven-transmembrane domain. In the case of CELSR/Flamingo/Starry night, their extracellular domains comprise nine cadherin repeats linked to a series of epidermal growth factor (EGF)-like and laminin globular (G)-like domains. The cadherin repeats contain sequence motifs that mediate calcium-dependent cell-cell adhesion by homophilic interactions. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR- autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. Three mammalian orthologs of Flamingo, Celsr1-3, are widely expressed in the nervous system from embryonic development until the adult stage. Each Celsr exhibits different expression patterns in the developing brain, suggesting that they serve distinct functions. Mutations of CELSR1 cause neural tube defects in the nervous system, while mutations of CELSR2 are associated with coronary heart disease. Moreover, CELSR1 and several other PCP signaling molecules, such as dishevelled, prickle, frizzled, have been shown to be upregulated in B lymphocytes of chronic lymphocytic leukemia patients. Celsr3 is expressed in both the developing and adult mouse brain. It has been functionally implicated in proper neuron migration and axon guidance in the CNS.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  877 IGCAVSCMALLTLLAIYAAFwRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCWVLTE 956
Cdd:cd15441     10 IGIGISLVLLVIAFLVLSCL-RGLQSNSNSIHKNLVACLLLAELLFLLGINQTENLFPCKLIAILLHYFYLSAFSWLLVE 88

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  957 AWQSYlavigRMRT--RLVRK---RF-LCLGWGLPALVVAVSVGFtRTKGYGTSSYCWLSLEGGLLYAFVGPAAVIVLVN 1030
Cdd:cd15441     89 SLHLY-----RMLTepRDINHghmRFyYLLGYGIPAIIVGLSVGL-RPDGYGNPDFCWLSVNETLIWSFAGPIAFVIVIT 162

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1031 MLIGIIVFNKLMARDGVsdKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDrRSVLFQALFAVFNSAQGFVITAVHCF 1110
Cdd:cd15441    163 LIIFILALRASCTLKRH--VLEKASVRTDLRSSFLLLPLLGATWVFGLLAVNE-DSELLHYLFAGLNFLQGLFIFLFYCI 239

                   ....*
gi 1783384314 1111 LRREV 1115
Cdd:cd15441    240 FNKKV 244

epidermal growth factor-like module-containing mucin-like hormone receptors, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group II adhesion GPCRs, including the epidermal growth factor (EGF)-module-containing, mucin-like hormone receptor (EMR1-4) and the leukocyte cell-surface antigen CD97, are primarily expressed in cells of the immune system. All EGF-TM7 receptors, which belong to the B2 subfamily of adhesion GPCRs, are members of group II, except for ETL (EGF-TM7-latrophilin related protein), which is classified into group I. Members of the EGF-TM7 receptors are characterized by the presence of varying number of N-terminal EGF-like domains, which play critical roles in ligand recognition and cell adhesion, linked by a stalk region to a class B seven-transmembrane domain. In the case of EMR2, alternative splicing results in four isoforms possessing either two (EGF1,2), three (EGF1,2,5), four (EGF1,2,3,5) or five (EGF1,2,3,4,5) EGF-like domains. Moreover, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. EMR2 shares strong sequence homology with CD97, differing by only six amino acids. CD97 is widely expressed on lymphocytes, monocytes, macrophages, dendritic cells, granulocytes and smooth muscle cells as well as in a variety of human tumors including colorectal, gastric, esophageal pancreatic, and thyroid carcinoma. However, unlike CD97, EMR2 is not found in those of CD97-positive tumor cells and is not expressed on lymphocytes but instead on monocytes, macrophages and granulocytes. CD97 has three known ligands: CD55, decay-accelerating factor for regulation of complement system; chondroitin sulfate, a glycosaminoglycan found in the extracellular matrix; and the integrin alpha5beta1, which play a role in angiogenesis. Although EMR2 does not effectively interact with CD55, the fourth EGF-like domain of this receptor binds to chondroitin sulfate to mediate cell attachment.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  877 IGCAVS--CM--ALLTLLaiyaaFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFCW 952
Cdd:cd15439     10 VGLIISllCLflAILTFL-----LCRSIRNTSTSLHLQLSLCLFLADLLFLVGIDRTDNKVLCSIIAGFLHYLFLACFAW 84

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  953 VLTEAWQSYLAV-----IGRMRTRLVRKRFLCL-GWGLPALVVAVSVGfTRTKGYGTSSYCWLSLEGGLLYAFVGPAAVI 1026
Cdd:cd15439     85 MFLEAVHLFLTVrnlkvVNYFSSHRFKKRFMYPvGYGLPAVIVAISAA-VNPQGYGTPKHCWLSMEKGFIWSFLGPVCVI 163

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1027 VLVNMLIGIIVF----NKLMARDgvSDKSKKQRAGASLWSSCVVLPLLALTWMSAVLAMTDRRSVLfQALFAVFNSAQGF 1102
Cdd:cd15439    164 IVINLVLFCLTLwilrEKLSSLN--AEVSTLKNTRLLTFKAIAQLFILGCTWILGLFQVGPVATVM-AYLFTITNSLQGV 240

                          250
                   ....*....|....*
gi 1783384314 1103 VITAVHCFLRREVQD 1117
Cdd:cd15439    241 FIFLVHCLLNRQVRE 255

orphan GPR116 and related proteins, group IV adhesion GPCRs, member of the class B2 family of seven-transmembrane G protein-coupled receptors; group VI adhesion GPCRs consist of orphan receptors GPR110, GPR111, GPR113, GPR115, GPR116, and closely related proteins. The adhesion receptors are characterized by the presence of large N-terminal extracellular domains containing multiple adhesion motifs, which play critical roles in ligand recognition as well as cell-cell adhesion and cell-matrix interactions, linked by a stalk region to a class B seven-transmembrane domain. GPR110 possesses a SEA box in the N-terminal has been identified as an oncogene over-expressed in lung and prostate cancer. GPR113 contains a hormone binding domain and one EGF (epidermal grown factor) domain. GPR112 has extremely long N-terminus (about 2,400 amino acids) containing a number of Ser/Thr-rich glycosylation sites and a pentraxin (PTX) domain. GPR116 has two C2-set immunoglobulin-like repeats, which is found in the members of the immunoglobulin superfamily of cell surface proteins, and a SEA (sea urchin sperm protein, enterokinase, and a grin)-box, which is present in the extracellular domain of the transmembrane mucin (MUC) family and known to enhance O-glycosylation. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions. However, several adhesion GPCRs, including GPR 111, GPR115, and CELSR1, are predicted to be non-cleavable at the GAIN domain because of the lack of a consensus catalytic triad sequence (His-Leu-Ser/Thr) within their GPS.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  877 IGCAVSCMALLTLLAIYAAFWRFIKSE-----RSIILLNFCLSILASNILILVG---QSRVLSKGVCTMTAAFLHFFFLS 948
Cdd:cd15932     10 VGLGISILSLVLCLIIEALVWKSVTKNktsymRHVCLVNIALSLLIADIWFIIGaaiSTPPNPSPACTAATFFIHFFYLA 89

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  949 SFCWVLTeawqsyLAVIGRMRTRLV-----RKRFL----CLGWGLPALVVAVSVGFTR-TKGYGTSSYCWLSL-EGGLLY 1017
Cdd:cd15932     90 LFFWMLT------LGLLLFYRLVLVfhdmsKSTMMaiafSLGYGCPLIIAIITVAATApQGGYTRKGVCWLNWdKTKALL 163

                          170       180       190       200       210       220       230       240
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314 1018 AFVGPAAVIVLVNMLIGIIVFNKLMaRDGVSDKSKKQRAGASLW-SSCVVL--PLLALTWMSAVLAMTDRRSVLFQALFA 1094
Cdd:cd15932    164 AFVIPALAIVVVNFIILIVVIFKLL-RPSVGERPSKDEKNALVQiGKSVAIltPLLGLTWGFGLGTMIDPKSLAFHIIFA 242

                          250       260
                   ....*....|....*....|....*.
gi 1783384314 1095 VFNSAQGFVITAVHCFLRREVQDVVK 1120
Cdd:cd15932    243 ILNSFQGFFILVFGTLLDSKVREALL 268

Latrophilin-1, member of the class B2 family of seven-transmembrane G protein-coupled receptors; Latrophilins (also called lectomedins or latrotoxin receptors) belong to Group I adhesion GPCRs, which also include ETL (EGF-TM7-latrophilin-related protein). These receptors are a member of the adhesion family (subclass B2) that belongs to the class B GPCRs. Three subtypes of latrophilins have been identified: LPH1 (latrophilin-1), LPH2, and LPH3. The latrophilin-1 is a brain-specific calcium-independent receptor of alpha-latrotoxin, a potent presynaptic neurotoxin from the venom of the black widow spider that induces massive neurotransmitter release from sensory and motor neurons as well as endocrine cells, leading to nerve-terminal degeneration. Latrophilin-2 and -3, although sharing strong sequence homology to latrophilin-1, do not bind alpha-latrotoxin. While latrophilin-3 is also brain specific, latrophilin-2 is ubiquitously distributed. The endogenous ligands for these two receptors are unknown. ETL, a seven transmembrane receptor containing EGF-like repeats is highly expressed in heart, where developmentally regulated, as well as in normal smooth cells. The function of the ETL is unknown. All adhesion GPCRs possess large N-terminal extracellular domains containing multiple structural motifs, which play critical roles in cell-cell adhesion and cell-matrix interactions, coupled to a seven-transmembrane domain. In addition, almost all adhesion receptors, except GPR123, contain an evolutionarily conserved GPCR-autoproteolysis inducing (GAIN) domain that undergoes autoproteolytic processing at the GPCR proteolysis site (GPS) motif located immediately N-terminal to the first transmembrane region, to generate N- and C-terminal fragments (NTF and CTF), which may serve important biological functions.

                           10        20        30        40        50        60        70        80
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  872 SVPLVIGCAVSCMALLTLLAIYAaFWRFIKSERSIILLNFCLSILASNILILVGQSRVLSKGVCTMTAAFLHFFFLSSFC 951
Cdd:cd16007      5 SVITWVGIVISLVCLAICISTFC-FLRGLQTDRNTIHKNLCINLFLAELLFLIGIDKTQYQIACPIFAGLLHFFFLAAFS 83

                           90       100       110       120       130       140       150       160
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1783384314  952 WVLTEAWQSYLAVIGRMRTRLVRKRFLCL-GWGLPALVVAVSVGFTrTKGYGTSSYCWLSLEGGLLYAFVGPAAVIVLVN 1030
Cdd:cd16007     84 WLCLEGVQLYLMLVEVFESEYSRKKYYYLcGYCFPALVVGISAAID-YRSYGTEKACWLRVDNYFIWSFIGPVSFVIVVN 162