Cyclin box fold superfamily; The cyclin box is a protein binding domain that functions in cell-cycle and transcriptional control. It is about 100 amino acids in length, composed of five helices, and is present in cyclins, transcription initiation factor IIB (TFIIB), and retinoblastoma tumour suppressor protein (Rb). Cyclins consist of 8 classes of cell cycle regulators that function as regulatory subunits of cyclin-dependent kinases (CDKs), which are serine/threonine kinases. The catalytic activities of CDKs are modulated not only by their interactions with cyclins but also by CDK inhibitors (CKIs). CDKs, cyclins and CKIs play key roles in transcription, epigenetic regulation, metabolism, stem cell self-renewal, neuronal functions, and spermatogenesis. TFIIB is a transcription factor that binds the TATA box. Members in this superfamily contain one or two copies of the cyclin box.

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1130413422 103 TPLDFLHIFHAIAVSTrpqllFSLPKLSPSQHLAVLTKQLLH--------CMACNQLLQFRGSMLALAMV--SLEMEKLI 172
Cdd:cd20529     2 TPAHFLEYYLSQGVLF-----VDDHDGLPSELLEKVKEYVRKyadffldlSLQDYAFLNYKPSLLAAACIaaARKALGLS 76

                  ...
gi 1130413422 173 PDW 175
Cdd:cd20529    77 PTW 79

Cyclin, N-terminal domain; Cyclins regulate cyclin dependent kinases (CDKs). Swiss:P22674 is a Uracil-DNA glycosylase that is related to other cyclins. Cyclins contain two domains of similar all-alpha fold, of which this family corresponds with the N-terminal domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|...
gi 1130413422  47 IAISCFFLAAKtVEEDErIPVLKVLARDSFCGCSSSEILRMERIILDKLNWDL 99
Cdd:pfam00134  76 VGVTCLFIAAK-YEEIY-PPTVEDLVYITDNAYTREEILRMERLILETLNFDL 126

Cyclin [Cell division and chromosome partitioning];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1130413422  29 VNVRKMPSNqahpKYLSCiAISCFFLAAKtVEEDERiPVLKVLARDSFCGCSSSEILRMERIILDKLNWDLHTATPLDFL 108
Cdd:COG5024   245 LSSRVVSLE----KYQLV-GISALFIASK-YEEVNC-PSIKDLVYATDGAFTRDDIIRAERYMLEVLDFNISWPSPMSFL 317

                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1130413422 109 HIFHAIA---VSTRPQLLFSLPkLSPSqhlavltkqllhcmaCNQLLQFRGSMLALAMVSLEMEKL 171
Cdd:COG5024   318 RRISKASdydIFSRTPAKFSSE-ISPV---------------DYKFIQISPSWCAAAAMYLSRKIL 367

cyclin box found in the cyclin-G (CCNG) family; The CCNG family includes two cyclins, CCNG1 and CCNG2. CCNG1 is the only cyclin that has either positive or negative effects on cell growth. It is associated with G2/M phase arrest in response to DNA damage. It is also involved in the development of human carcinoma. CCNG2 may play a role in growth regulation and in negative regulation of cell cycle progression. It has been identified as a tumor suppressor in several cancers. Members of this family contain one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*..
gi 1130413422  39 AHPKYLSCIAISCFFLAAKTVEEDERIPVLKVLARDSFCGCSSSEILRMERIILDKL 95
Cdd:cd20523    38 VKPKHLACITVSCFHIAIKSVEEDQNIPSAEDLIRISQCGCTAADLMRMEGIILEKL 94

cyclin box found in cyclin-G1 (CCNG1) and similar proteins; CCNG1 is the only cyclin that has either positive or negative effects on cell growth. It is associated with G2/M phase arrest in response to DNA damage. It is also involved in the development of human carcinoma. CCNG1 contains one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|
gi 1130413422  38 QAHPKYLSCIAISCFFLAAKTVEEDERIPVLKVLARDSFCGCSSSEILRMERIILDKLNW 97
Cdd:cd20583    38 KVQPKHLGCVGLSCFYLAVKAIEEERNVPLATDLIRISQYRFTVSDMMRMEKIILEKLCW 97

cyclin box found in Saccharomyces cerevisiae G1/S-specific cyclins (ScCLNs) and similar proteins; ScCLNs, including ScCLN1-3, are essential for the control of the cell cycle at the G1/S (start) transition in Saccharomyces. ScCLN1 and ScCLN2 interact with the CDC28 protein kinase to form maturation promoting factor (MPF). ScCLN3 may be an upstream activator of the G1 cyclins that directly initiate G1/S transition. This family also includes Schizosaccharomyces pombe cyclin puc1, which contributes to negative regulation of the timing of sexual development in fission yeast, and functions at the transition between cycling and non-cycling cells. It interacts with protein kinase A. Members of this family contain one cyclin box. The cyclin box is a protein binding domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....*....
gi 1130413422  42 KYLSCIAISCFFLAAKTVEEDERIPVLKVLARdsFCGCSSSE--ILRMERIILDKLNWD 98
Cdd:cd20559    39 KHYQLVGCTCLWIASKFWESKARVPLLSELSK--MCCNSYGEelFIQMEMHILNTLNWD 95

Cyclin [Cell division and chromosome partitioning];

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 1130413422  29 VNVRKMPSNqahpKYLSCiAISCFFLAAKtVEEDERiPVLKVLARDSFCGCSSSEILRMERIILDKLNWDLHTATPLDFL 108
Cdd:COG5024   245 LSSRVVSLE----KYQLV-GISALFIASK-YEEVNC-PSIKDLVYATDGAFTRDDIIRAERYMLEVLDFNISWPSPMSFL 317

                          90       100       110       120       130       140
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 1130413422 109 HIFHAIA---VSTRPQLLFSLPkLSPSqhlavltkqllhcmaCNQLLQFRGSMLALAMVSLEMEKL 171
Cdd:COG5024   318 RRISKASdydIFSRTPAKFSSE-ISPV---------------DYKFIQISPSWCAAAAMYLSRKIL 367

first cyclin box found in G1/S-specific cyclin-E1 (CCNE1); CCNE1 is essential for the control of the cell cycle at the G1/S (start) transition. It interacts with CDK2 protein kinase to form a serine/threonine kinase holoenzyme complex. CCNE1 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1130413422  44 LSCIAISCFFLAAKTveEDERIPVLKVLARDSFCGCSSSEILRMERIILDKLNW 97
Cdd:cd20579    86 LQLIGISSLFIAAKL--EEIYPPKLHQFAYVTDGACTEDEILSMELIIMKALKW 137

first cyclin box found in G1/S-specific cyclin-E (CCNE) family; The CCNE family includes two E-type cyclins, CCNE1 and CCNE2. CCNE1 is essential for the control of the cell cycle at the G1/S (start) transition. It interacts with CDK2 protein kinase to form a serine/threonine kinase holoenzyme complex. CCNE2 is essential for the control of the cell cycle at the late G1 and early S phase. It interacts with the CDK2 (in vivo) and CDK3 (in vitro) protein kinases to form a serine/threonine kinase holoenzyme complexes. Members of this family contain two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1130413422  44 LSCIAISCFFLAAKTveEDERIPVLKVLARDSFCGCSSSEILRMERIILDKLNW 97
Cdd:cd20519    80 LQLIGITCLFIAAKL--EEIYPPKLSEFAYVTDGACTEDEILTMELIILKALNW 131

Cyclin box fold superfamily; The cyclin box is a protein binding domain that functions in cell-cycle and transcriptional control. It is about 100 amino acids in length, composed of five helices, and is present in cyclins, transcription initiation factor IIB (TFIIB), and retinoblastoma tumour suppressor protein (Rb). Cyclins consist of 8 classes of cell cycle regulators that function as regulatory subunits of cyclin-dependent kinases (CDKs), which are serine/threonine kinases. The catalytic activities of CDKs are modulated not only by their interactions with cyclins but also by CDK inhibitors (CKIs). CDKs, cyclins and CKIs play key roles in transcription, epigenetic regulation, metabolism, stem cell self-renewal, neuronal functions, and spermatogenesis. TFIIB is a transcription factor that binds the TATA box. Members in this superfamily contain one or two copies of the cyclin box.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|.
gi 1130413422  40 HPKYLSCIAISCFFLAAKtveEDERIPVLKVLARdsFCGCSSSEILRMERI 90
Cdd:cd00043    37 LGRSPELIAAACLYLACK---LEELPRTLKEIAK--VSGVSEKELRKAEKE 82

first cyclin box found in G1/S-specific cyclin-E2 (CCNE2); CCNE2 is essential for the control of the cell cycle at the late G1 and early S phase. It interacts with the CDK2 (in vivo) and CDK3 (in vitro) protein kinases to form a serine/threonine kinase holoenzyme complexes. CCNE2 contains two cyclin boxes. This model corresponds to the first one. The cyclin box is a protein binding domain.

                          10        20        30        40        50
                  ....*....|....*....|....*....|....*....|....*....|....
gi 1130413422  44 LSCIAISCFFLAAKTveEDERIPVLKVLARDSFCGCSSSEILRMERIILDKLNW 97
Cdd:cd20580    86 LQLIGITSLFIASKL--EEIYPPKLHEFAYVTDGACSEDDILDMELIILKALKW 137