Rossmann-fold NAD(P)(+)-binding proteins; A large family of proteins that share a Rossmann-fold NAD(P)H/NAD(P)(+) binding (NADB) domain. The NADB domain is found in numerous dehydrogenases of metabolic pathways such as glycolysis, and many other redox enzymes. NAD binding involves numerous hydrogen-bonds and van der Waals contacts, in particular H-bonding of residues in a turn between the first strand and the subsequent helix of the Rossmann-fold topology. Characteristically, this turn exhibits a consensus binding pattern similar to GXGXXG, in which the first 2 glycines participate in NAD(P)-binding, and the third facilitates close packing of the helix to the beta-strand. Typically, proteins in this family contain a second domain in addition to the NADB domain, which is responsible for specifically binding a substrate and catalyzing a particular enzymatic reaction.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  19 KSVFILGASGETGRVLLKEILEQGLFSKVTLIGRRKLTFdEEAYKNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:cd05250    1 KTALVLGATGLVGKHLLRELLKSPYYSKVTAIVRRKLTF-PEAKEKLVQIVVDFERLDEYLEAFQNPDVGFCCLGTTRKK 79

                 ...
gi 148728170  99 AGA 101
Cdd:cd05250   80 AGS 82

CC3(TIP30)-like, atypical (a) SDRs; Atypical SDRs in this subgroup include CC3 (also known as TIP30) which is implicated in tumor suppression. Atypical SDRs are distinct from classical SDRs. Members of this subgroup have a glycine rich NAD(P)-binding motif that resembles the extended SDRs, and have an active site triad of the SDRs (YXXXK and upstream Ser), although the upstream Asn of the usual SDR active site is substituted with Asp. For CC3, the Tyr of the triad is displaced compared to the usual SDRs and the protein is monomeric, both these observations suggest that the usual SDR catalytic activity is not present. NADP appears to serve an important role as a ligand, and may be important in the interaction with other macromolecules. Atypical SDRs generally lack the catalytic residues characteristic of the SDRs, and their glycine-rich NAD(P)-binding motif is often different from the forms normally seen in classical or extended SDRs. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  19 KSVFILGASGETGRVLLKEILEQGLFSKVTLIGRRKLTFdEEAYKNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:cd05250    1 KTALVLGATGLVGKHLLRELLKSPYYSKVTAIVRRKLTF-PEAKEKLVQIVVDFERLDEYLEAFQNPDVGFCCLGTTRKK 79

                 ...
gi 148728170  99 AGA 101
Cdd:cd05250   80 AGS 82

Putative NADH-flavin reductase [General function prediction only];

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  21 VFILGASGETGRVLLKEILEQGLfsKVTLIGRR--KLTFDEEaykNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:COG2910    2 IAVIGATGRVGSLIVREALARGH--EVTALVRNpeKLPDEHP---GLTVVVGDVLDPAAVAEALAGADAVVSALGAGGGN 76

                 ....
gi 148728170  99 AGAV 102
Cdd:COG2910   77 PTTV 80

CC3(TIP30)-like, atypical (a) SDRs; Atypical SDRs in this subgroup include CC3 (also known as TIP30) which is implicated in tumor suppression. Atypical SDRs are distinct from classical SDRs. Members of this subgroup have a glycine rich NAD(P)-binding motif that resembles the extended SDRs, and have an active site triad of the SDRs (YXXXK and upstream Ser), although the upstream Asn of the usual SDR active site is substituted with Asp. For CC3, the Tyr of the triad is displaced compared to the usual SDRs and the protein is monomeric, both these observations suggest that the usual SDR catalytic activity is not present. NADP appears to serve an important role as a ligand, and may be important in the interaction with other macromolecules. Atypical SDRs generally lack the catalytic residues characteristic of the SDRs, and their glycine-rich NAD(P)-binding motif is often different from the forms normally seen in classical or extended SDRs. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  19 KSVFILGASGETGRVLLKEILEQGLFSKVTLIGRRKLTFdEEAYKNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:cd05250    1 KTALVLGATGLVGKHLLRELLKSPYYSKVTAIVRRKLTF-PEAKEKLVQIVVDFERLDEYLEAFQNPDVGFCCLGTTRKK 79

                 ...
gi 148728170  99 AGA 101
Cdd:cd05250   80 AGS 82

NAD(P)H-binding;

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170   25 GASGETGRVLLKEILEQGLfsKVTLIGRR--KLTFDEEaykNVNQEVV--DFEKLDDYASAFQGHDVGFCCLGTTRGKAG 100
Cdd:pfam13460   1 GATGKIGRLLVKQLLARGH--EVTALVRNpeKLADLED---HPGVEVVdgDVLDPDDLAEALAGQDAVISALGGGGTDET 75

                  ....*
gi 148728170  101 AVRKA 105
Cdd:pfam13460  76 GAKNI 80

biliverdin IX beta reductase (BVR-B, aka flavin reductase)-like proteins; atypical (a) SDRs; Human BVR-B catalyzes pyridine nucleotide-dependent production of bilirubin-IX beta during fetal development; in the adult BVR-B has flavin and ferric reductase activities. Human BVR-B catalyzes the reduction of FMN, FAD, and riboflavin. Recognition of flavin occurs mostly by hydrophobic interactions, accounting for the broad substrate specificity. Atypical SDRs are distinct from classical SDRs. BVR-B does not share the key catalytic triad, or conserved tyrosine typical of SDRs. The glycine-rich NADP-binding motif of BVR-B is GXXGXXG, which is similar but not identical to the pattern seen in extended SDRs. Atypical SDRs generally lack the catalytic residues characteristic of the SDRs, and their glycine-rich NAD(P)-binding motif is often different from the forms normally seen in classical or extended SDRs. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 148728170  23 ILGASGETGRVLLKEILEQGLfsKVTLIGRRKlTFDEEAYKNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:cd05244    4 IIGATGRTGSAIVREALARGH--EVTALVRDP-AKLPAEHEKLKVVQGDVLDLEDVKEALEGQDAVISALGTRNDL 76

phenylcoumaran benzylic ether reductase (PCBER) like, atypical (a) SDRs; PCBER and pinoresinol-lariciresinol reductases are NADPH-dependent aromatic alcohol reductases, and are atypical members of the SDR family. Other proteins in this subgroup are identified as eugenol synthase. These proteins contain an N-terminus characteristic of NAD(P)-binding proteins and a small C-terminal domain presumed to be involved in substrate binding, but they do not have the conserved active site Tyr residue typically found in SDRs. Numerous other members have unknown functions. The glycine rich NADP-binding motif in this subgroup is of 2 forms: GXGXXG and G[GA]XGXXG; it tends to be atypical compared with the forms generally seen in classical or extended SDRs. The usual SDR active site tetrad is not present, but a critical active site Lys at the usual SDR position has been identified in various members, though other charged and polar residues are found at this position in this subgroup. Atypical SDR-related proteins retain the Rossmann fold of the SDRs, but have limited sequence identity and generally lack the catalytic properties of the archetypical members. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 148728170  20 SVFILGASGETGRVLLKEILEQGLFSkVTLIGRRKLTFDEEAY-KNVNQEVVDFEKLDDYASAFQGHDVGFCCLGTT 95
Cdd:cd05259    1 KIAIAGATGTLGGPIVSALLASPGFT-VTVLTRPSSTSSNEFQpSGVKVVPVDYASHESLVAALKGVDAVISALGGA 76

atypical (a) SDRs, subgroup 5; This subgroup contains atypical SDRs, some of which are identified as putative NAD(P)-dependent epimerases, one as a putative NAD-dependent epimerase/dehydratase. Atypical SDRs are distinct from classical SDRs. Members of this subgroup have a glycine-rich NAD(P)-binding motif that is very similar to the extended SDRs, GXXGXXG, and binds NADP. Generally, this subgroup has poor conservation of the active site tetrad; however, individual sequences do contain matches to the YXXXK active site motif, the upstream Ser, and there is a highly conserved Asp in place of the usual active site Asn throughout the subgroup. Atypical SDRs generally lack the catalytic residues characteristic of the SDRs, and their glycine-rich NAD(P)-binding motif is often different from the forms normally seen in classical or extended SDRs. Atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), progesterone 5-beta-reductase like proteins, phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  21 VFILGASGETGRVLLKEILEQGlfSKVTLIGRRKLTFDEEAYKNVnqEVV--DFEKLDDYASAFQGHDVGFCCLGTTRGK 98
Cdd:cd05243    2 VLVVGATGKVGRHVVRELLDRG--YQVRALVRDPSQAEKLEAAGA--EVVvgDLTDAESLAAALEGIDAVISAAGSGGKG 77

                 ....*.
gi 148728170  99 AGAVRK 104
Cdd:cd05243   78 GPRTEA 83

N-terminal NAD(P)-binding domain of Vibrio cholerae aspartate beta-semialdehyde dehydrogenase 2 (ASADH2) and similar proteins; The family corresponds to a new branch of bacterial ASADH enzymes that has a similar overall fold and domain organization but sharing less sequence homology with the other bacterial ASADHs. The second isoform of ASADH in Vibrio cholerae is one of the prototypes of this family. It also includes ASADHs from Streptococcus pneumoniae, Mycobacterium tuberculosis, Thermus thermophilus, as well as from eukaryotes. ASADH (EC 1.2.1.11), also called ASA dehydrogenase (ASD), or aspartate-beta-semialdehyde dehydrogenase, catalyzes the NADPH-dependent formation of L-aspartate-semialdehyde (ASA) by the reductive dephosphorylation of L-aspartyl-4-phosphate, which is the second step of the aspartate biosynthetic pathway. ASA can either be further reduced to homoserine, which leads to methionine, threonine, or isoleucine, or it can be condensed with pyruvate and cyclized into dihydrodipicolinate, and then converted into diaminopimelate, a component of bacterial cell walls, and finally decarboxylated to produce lysine. ASADH contains an N-terminal Rossmann fold NAD(P) binding domain and a C-terminal glyceraldehyde-3-phosphate dehydrogenase (GAPDH)-like catalytic domain.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  20 SVFILGASGETGRVLLKeILEQGLF--SKVTLIG--R---RKLTFDEEAYknvnqEVVDFEKlddyaSAFQGHDVGFCCL 92
Cdd:cd02316    2 NVAIVGATGAVGQEMLK-VLEERNFpvSELRLLAsaRsagKTLEFKGKEL-----TVEELTE-----DSFKGVDIALFSA 70

                         90
                 ....*....|....*
gi 148728170  93 GttrgkaGAVRKAYA 107
Cdd:cd02316   71 G------GSVSKEFA 79

NmrA (a transcriptional regulator) and triphenylmethane reductase (TMR) like proteins, subgroup 1, atypical (a) SDRs; Atypical SDRs related to NMRa, TMR, and HSCARG (an NADPH sensor). This subgroup resembles the SDRs and has a partially conserved characteristic [ST]GXXGXXG NAD-binding motif, but lacks the conserved active site residues. NmrA is a negative transcriptional regulator of various fungi, involved in the post-translational modulation of the GATA-type transcription factor AreA. NmrA lacks the canonical GXXGXXG NAD-binding motif and has altered residues at the catalytic triad, including a Met instead of the critical Tyr residue. NmrA may bind nucleotides but appears to lack any dehydrogenase activity. HSCARG has been identified as a putative NADP-sensing molecule, and redistributes and restructures in response to NADPH/NADP ratios. Like NmrA, it lacks most of the active site residues of the SDR family, but has an NAD(P)-binding motif similar to the extended SDR family, GXXGXXG. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Atypical SDRs are distinct from classical SDRs. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30        40        50        60        70        80
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 148728170  23 ILGASGETGRVLLKEILEQGlfSKVTLIGRRKLTFDEEAYKNVNQEVVDFEKLDDYASAFQGHDVGFCCL---GTTRGKA 99
Cdd:cd05231    3 VTGATGRIGSKVATTLLEAG--RPVRALVRSDERAAALAARGAEVVVGDLDDPAVLAAALAGVDAVFFLAppaPTADARP 80

                 ....*.
gi 148728170 100 GAVRKA 105
Cdd:cd05231   81 GYVQAA 86

progesterone 5-beta-reductase-like proteins (5beta-POR), atypical (a) SDRs; 5beta-POR catalyzes the reduction of progesterone to 5beta-pregnane-3,20-dione in Digitalis plants. This subgroup of atypical-extended SDRs, shares the structure of an extended SDR, but has a different glycine-rich nucleotide binding motif (GXXGXXG) and lacks the YXXXK active site motif of classical and extended SDRs. Tyr-179 and Lys 147 are present in the active site, but not in the usual SDR configuration. Given these differences, it has been proposed that this subfamily represents a new SDR class. Other atypical SDRs include biliverdin IX beta reductase (BVR-B,aka flavin reductase), NMRa (a negative transcriptional regulator of various fungi), phenylcoumaran benzylic ether and pinoresinol-lariciresinol reductases, phenylpropene synthases, eugenol synthase, triphenylmethane reductase, isoflavone reductases, and others. SDRs are a functionally diverse family of oxidoreductases that have a single domain with a structurally conserved Rossmann fold, an NAD(P)(H)-binding region, and a structurally diverse C-terminal region. Sequence identity between different SDR enzymes is typically in the 15-30% range; they catalyze a wide range of activities including the metabolism of steroids, cofactors, carbohydrates, lipids, aromatic compounds, and amino acids, and act in redox sensing. Classical SDRs have an TGXXX[AG]XG cofactor binding motif and a YXXXK active site motif, with the Tyr residue of the active site motif serving as a critical catalytic residue (Tyr-151, human 15-hydroxyprostaglandin dehydrogenase numbering). In addition to the Tyr and Lys, there is often an upstream Ser and/or an Asn, contributing to the active site; while substrate binding is in the C-terminal region, which determines specificity. The standard reaction mechanism is a 4-pro-S hydride transfer and proton relay involving the conserved Tyr and Lys, a water molecule stabilized by Asn, and nicotinamide. In addition to the Rossmann fold core region typical of all SDRs, extended SDRs have a less conserved C-terminal extension of approximately 100 amino acids, and typically have a TGXXGXXG cofactor binding motif. Complex (multidomain) SDRs such as ketoreductase domains of fatty acid synthase have a GGXGXXG NAD(P)-binding motif and an altered active site motif (YXXXN). Fungal type ketoacyl reductases have a TGXXXGX(1-2)G NAD(P)-binding motif.

                         10        20        30
                 ....*....|....*....|....*....|....*...
gi 148728170  20 SVFILGASGETGRVLLKEILEQ-GLFSKVTLIGRRKLT 56
Cdd:cd08948    1 VALVVGATGISGWALVEHLLSDpGTWWKVYGLSRRPLP 38