Aldehyde reductase (AKR1A1) is a member of the aldo-keto reductase superfamily, which consists of more than 40 known enzymes and proteins that includes variety of monomeric NADPH-dependent oxidoreductases, such as aldehyde reductase. Aldehyde reductase has wide substrate specificities for carbonyl compounds. These enzymes are implicated in the development of diabetic complications by catalyzing the reduction of glucose to sorbitol. Aldehyde reductase possess a structure with a beta-alpha-beta fold 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. This binding is more similar to FAD- than to NAD(P)-binding oxidoreductases. AKR1A1 is involved in the reduction of biogenic and xenobiotic aldehydes and is present in virtually every tissue.
Aldo-Keto Reductase Family 1 Member C2 (AKR1C2) plays a role in concert with the 5-α 5-β-Steroid Reductases to convert Steroid hormones into the 3-α 5-α and 3-α 5-β-Tetrahydrosteroids. AKR1C2 catalyzes the inactivation of the most potent androgen 5-α-Dihydrotestosterone (5-α-DHT) to 5-α-Androstane-3-α, 17-β-diol (3-α-diol).
Aldo-keto reductases comprise of AKR1C1-AKR1C4, four enzymes that catalyze NADPH dependent reductions and have been implicated in biosynthesis, intermediary metabolism, and detoxification. there is a strong correlation between the expression levels of these family members and the malignant transformation as well as the resistance to cancer therapy. Type I human hepatic 3alpha-hydroxysteroid dehydrogenase (AKR1C4) plays a significant role in bile acid biosynthesis, steroid hormone metabolism, and xenobiotic metabolism.