1j96
From Proteopedia
Human 3alpha-HSD type 3 in Ternary Complex with NADP and Testosterone
Structural highlights
Disease[AK1C2_HUMAN] Defects in AKR1C2 are a cause of 46,XY sex reversal type 8 (SRXY8) [MIM:614279]. A disorder of sex development. Affected individuals have a 46,XY karyotype but present as phenotypically normal females.[1] Function[AK1C2_HUMAN] Works in concert with the 5-alpha/5-beta-steroid reductases to convert steroid hormones into the 3-alpha/5-alpha and 3-alpha/5-beta-tetrahydrosteroids. Catalyzes the inactivation of the most potent androgen 5-alpha-dihydrotestosterone (5-alpha-DHT) to 5-alpha-androstane-3-alpha,17-beta-diol (3-alpha-diol). Has a high bile-binding ability.[2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe first crystallographic structure of human type 3 3alpha-hydroxysteroid dehydrogenase (3alpha-HSD3, AKR1C2), an enzyme playing a critical role in steroid hormone metabolism, has been determined in complex with testosterone and NADP at 1.25-A resolution. The enzyme's 17beta-HSD activity was studied in comparison with its 3alpha-HSD activity. The enzyme catalyzes the inactivation of dihydrotestosterone into 5alpha-androstane-3alpha,17beta-diol (3alpha-diol) as well as the transformation of androstenedione into testosterone. Using our homogeneous and highly active enzyme preparation, we have obtained 150-fold higher 3alpha-HSD specificity as compared with the former reports in the literature. Although the rat and the human 3alpha-HSDs share 81% sequence homology, our structure reveals significantly different geometries of the active sites. Substitution of the Ser(222) by a histidine in the human enzyme may compel the steroid to adopt a different binding to that previously described for the rat (Bennett, M. J., Albert, R. H., Jez, J. M., Ma, H., Penning, T. M., and Lewis, M. (1997) Structure 5, 799-T812). Furthermore, we showed that the affinity for the cofactor is higher in the human 3alpha-HSD3 than the rat enzyme due to the presence of additional hydrogen bonds on the adenine moiety and that the cofactor is present under its reduced form in the active site in our preparation. Structure of the human 3alpha-hydroxysteroid dehydrogenase type 3 in complex with testosterone and NADP at 1.25-A resolution.,Nahoum V, Gangloff A, Legrand P, Zhu DW, Cantin L, Zhorov BS, Luu-The V, Labrie F, Breton R, Lin SX J Biol Chem. 2001 Nov 9;276(45):42091-8. Epub 2001 Aug 20. PMID:11514561[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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