InterPro domain: IPR023210

The aldo-keto reductase family includes a number of related monomeric NADPH-dependent oxidoreductases, such as aldehyde reductase, aldose reductase, prostaglandin F synthase, xylose reductase, rho crystallin, and many others [ 1 ]. All possess a similar structure, with a beta-alpha-beta fold characteristic of nucleotide binding proteins [ 2 ]. The fold comprises a parallel beta-8/alpha-8-barrel, which contains a novel NADP-binding motif. The binding site is located in a large,deep, elliptical pocket in the C-terminal end of the beta sheet, the substrate being bound in an extended conformation. The hydrophobicnature of the pocket favours aromatic and apolar substrates over highly polar ones [ 3 ].

Binding of the NADPH coenzyme causes a massive conformational change, reorienting a loop, effectively locking thecoenzyme in place. This binding is more similar to FAD- than to NAD(P)-binding oxidoreductases [ 4 ].

Some proteins of this entry contain a K+ ion channel beta chain regulatory domain; these are reported to have oxidoreductase activity [ 5 ].

This entry represents the NADP-dependent oxidoreductase domain found in these proteins.

1. The aldo-keto reductase superfamily. cDNAs and deduced amino acid sequences of human aldehyde and aldose reductases. J. Biol. Chem. 264, 9547-51
2. Sequence analysis of bovine lens aldose reductase. J. Biol. Chem. 265, 3628-35
3. An unlikely sugar substrate site in the 1.65 A structure of the human aldose reductase holoenzyme implicated in diabetic complications. Science 257, 81-4
4. The crystal structure of the aldose reductase.NADPH binary complex. J. Biol. Chem. 267, 24841-7
5. Structure of the cytoplasmic beta subunit-T1 assembly of voltage-dependent K+ channels. Science 289, 123-7