The short-chain dehydrogenases/reductases family (SDR) [1] is a very large family of enzymes, most of which are known to be NAD- or NADP-dependent oxidoreductases. As the first member of this family to be characterized was Drosophila alcohol dehydrogenase, this family used to be called [2,3,4] 'insect-type', or 'short-chain' alcohol dehydrogenases. Most member of this family are proteins of about 250 to 300 amino acid residues. The proteins currently known to belong to this family are listed below.

• Alcohol dehydrogenase (EC 1.1.1.1) from insects such as Drosophila.
• Acetoin dehydrogenase (EC 1.1.1.5) from Klebsiella terrigena (gene budC).
• D-β-hydroxybutyrate dehydrogenase (BDH) (EC 1.1.1.30) from mammals.
• Acetoacetyl-CoA reductase (EC 1.1.1.36) from various bacterial species (gene phbB or phaB).
• Glucose 1-dehydrogenase (EC 1.1.1.47) from Bacillus.
• 3-β-hydroxysteroid dehydrogenase (EC 1.1.1.51) from Comomonas testosteroni.
• 20-β-hydroxysteroid dehydrogenase (EC 1.1.1.53) from Streptomyces hydrogenans.
• Ribitol 2-dehydrogenase (EC 1.1.1.56) (RDH) from Klebsiella aerogenes.
• Estradiol 17-β-dehydrogenase (EC 1.1.1.62) from human.
• Gluconate 5-dehydrogenase (EC 1.1.1.69) from Gluconobacter oxydans (gene gno).
• 3-oxoacyl-[acyl-carrier protein] reductase (EC 1.1.1.100) from Escherichia coli (gene fabG) and from plants.
• Retinol dehydrogenase (EC 1.1.1.105) from mammals.
• 2-deoxy-d-gluconate 3-dehydrogenase (EC 1.1.1.125) from Escherichia coli and Erwinia chrysanthemi (gene kduD).
• Sorbitol-6-phosphate 2-dehydrogenase (EC 1.1.1.140) from Escherichia coli (gene gutD) and from Klebsiella pneumoniae (gene sorD).
• 15-hydroxyprostaglandin dehydrogenase (NAD+) (EC 1.1.1.141) from human.
• Corticosteroid 11-β-dehydrogenase (EC 1.1.1.146) (11-DH) from mammals.
• 7-α-hydroxysteroid dehydrogenase (EC 1.1.1.159) from Escherichia coli (gene hdhA), Eubacterium strain VPI 12708 (gene baiA) and from Clostridium sordellii.
• NADPH-dependent carbonyl reductase (EC 1.1.1.184) from mammals.
• Tropinone reductase-I (EC 1.1.1.206) and -II (EC 1.1.1.236) from plants.
• N-acylmannosamine 1-dehydrogenase (EC 1.1.1.233) from Flavobacterium strain 141-8.
• D-arabinitol 2-dehydrogenase (ribulose forming) (EC 1.1.1.250) from fungi.
• Tetrahydroxynaphthalene reductase (EC 1.1.1.252) from Magnaporthe grisea.
• Pteridine reductase 1 (EC 1.5.1.33) (gene PTR1) from Leishmania.
• 2,5-dichloro-2,5-cyclohexadiene-1,4-diol dehydrogenase (EC 1.1.-.-) from Pseudomonas paucimobilis.
• Cis-1,2-dihydroxy-3,4-cyclohexadiene-1-carboxylate dehydrogenase (EC 1.3.1. -) from Acinetobacter calcoaceticus (gene benD) and Pseudomonas putida (gene xylL).
• Biphenyl-2,3-dihydro-2,3-diol dehydrogenase (EC 1.3.1.-) (gene bphB) from various Pseudomonaceae.
• Cis-toluene dihydrodiol dehydrogenase (EC 1.3.1.-) from Pseudomonas putida (gene todD).
• Cis-benzene glycol dehydrogenase (EC 1.3.1.19) from Pseudomonas putida (gene bnzE).
• 2,3-dihydro-2,3-dihydroxybenzoate dehydrogenase (EC 1.3.1.28) from Escherichia coli (gene entA) and Bacillus subtilis (gene dhbA).
• Dihydropteridine reductase (EC 1.5.1.34) (HDHPR) from mammals.
• Lignin degradation enzyme ligD from Pseudomonas paucimobilis.
• Agropine synthesis reductase from Agrobacterium plasmids (gene mas1).
• Versicolorin reductase from Aspergillus parasiticus (gene VER1).
• Putative keto-acyl reductases from Streptomyces polyketide biosynthesis operons.
• A trifunctional hydratase-dehydrogenase-epimerase from the peroxisomal β-oxidation system of Candida tropicalis. This protein contains two tandemly repeated 'short-chain dehydrogenase-type' domain in its N-terminal extremity.
• Nodulation protein nodG from species of Azospirillum and Rhizobium which is probably involved in the modification of the nodulation Nod factor fatty acyl chain.
• Nitrogen fixation protein fixR from Bradyrhizobium japonicum.
• Bacillus subtilis protein dltE which is involved in the biosynthesis of D- alanyl-lipoteichoic acid.
• Human follicular variant translocation protein 1 (FVT1).
• Mouse adipocyte protein p27.
• Mouse protein Ke 6.
• Maize sex determination protein TASSELSEED 2.
• Sarcophaga peregrina 25 Kd development specific protein.
• Drosophila fat body protein P6.
• A Listeria monocytogenes hypothetical protein encoded in the internalins gene region.
• Escherichia coli hypothetical protein yciK.
• Escherichia coli hypothetical protein ydfG.
• Escherichia coli hypothetical protein yjgI.
• Escherichia coli hypothetical protein yjgU.
• Escherichia coli hypothetical protein yohF.
• Bacillus subtilis hypothetical protein yoxD.
• Bacillus subtilis hypothetical protein ywfD.
• Bacillus subtilis hypothetical protein ywfH.
• Yeast hypothetical protein YIL124w.
• Yeast hypothetical protein YIR035c.
• Yeast hypothetical protein YIR036c.
• Yeast hypothetical protein YKL055c.
• Fission yeast hypothetical protein SpAC23D3.11.

We use as a signature pattern for this family of proteins one of the best conserved regions which includes two perfectly conserved residues, a tyrosine and a lysine. The tyrosine residue participates in the catalytic mechanism.