Aldo Keto Reductase Family 1, Member D1 (AKR1D1)

Human delta(4)-3-oxosteroid 5-beta-reductase (steroid 5-beta-reductase) catalyzes 5-beta-reduction of bile acid intermediates and steroid hormones carrying a delta(4)-3-one structure.

The full-length cDNA encodes a peptide of 326 amino acids with a relative mass of 37,380 Da. Northern blot analysis of human liver RNA identified a 2.7-kb transcript. The authors inserted the 5-beta-reductase cDNA into an expression vector and transfected it into COS cells. The recombinant protein was detected by immunoblot analysis using a monoclonal antibody against rat 5-beta-reductase. Recombinant 5-beta-reductase showed 5-beta-reductase activity against several substrates, as detected by high-performance liquid chromatography.