Department of Pediatrics, Cornell University Medical College, New York, NY 10021, USA.
J Steroid Biochem Mol Biol. 1992 Dec;43(8):1083-8. doi: 10.1016/0960-0760(92)90335-G.
3α-Hydroxysteroid dehydrogenase and related enzymes play important roles in the metabolism of endogenous compounds including androgens, corticosteroid, prostaglandins and bile acids, as well as drugs and xenobiotics such as benzo(a)pyrene. Complementary DNA clones encoding 3α-hydroxysteroid dehydrogenase were isolated from a rat liver cDNA lambda gt11 expression library using monoclonal antibodies as probes. A full-length cDNA clone of 1286 base pairs contained an open reading frame encoding a protein of 322 amino acids with an estimated M(w) of 37 kD. When expressed in E. coli, the encoded protein migrated to the same position on SDS-polycrylamide gels as the enzyme in rat liver cytosols. The protein expressed in bacteria was highly active in androsterone oxidation in the presence of NAD as cofactor and this activity was inhibited by indomethacin, a potent inhibitor of 3α-hydroxysteroid dehydrogenase. The predicted amino acid sequence of 3α-hydroxysteroid d dehydrogenase was related to sequences of several other aldo-keto reductases such as bovine prostaglandin F synthase, human chlordecone reductase, human aldose reductase, human aldehyde reductase and frog lens epsilon-crystallin, suggesting that these proteins belong to the same gene family. Recently, we have found that monoclonal antibodies against 3α-hydroxysteroid dehydrogenase also recognized multiple antigenically related proteins in rat lung, kidney and testis. Further screening of liver, lung and kidney cDNA libraries using these monoclonal antibodies as probes resulted in the isolation of additional five different cDNAs encoding proteins with high degree of structural homology to rat liver 3α-hydroxysteroid dehydrogenase.
3α-羟甾类脱氢酶和相关酶在包括雄激素、皮质甾类、前列腺素和胆酸在内的内源性化合物以及包括苯并(a)芘在内的药物和外源化学物质的代谢中起着重要作用。使用单克隆抗体作为探针，从大鼠肝 cDNA λgt11 表达文库中分离到编码 3α-羟甾类脱氢酶的 cDNA 克隆。全长 1286 个碱基对的 cDNA 克隆含有一个开放阅读框，编码一个 322 个氨基酸的蛋白质，估计分子量为 37 kD。当在大肠杆菌中表达时，编码的蛋白质在 SDS-聚丙烯酰胺凝胶上迁移到与大鼠肝胞质溶胶中酶相同的位置。在 NAD 作为辅助因子存在的情况下，在细菌中表达的蛋白质在雄甾酮氧化中具有高度活性，并且该活性被吲哚美辛抑制，吲哚美辛是 3α-羟甾类脱氢酶的一种有效抑制剂。3α-羟甾类脱氢酶的预测氨基酸序列与几种其他醛酮还原酶的序列有关，如牛前列腺素 F 合酶、人氯丹还原酶、人醛糖还原酶、人醛还原酶和蛙晶状体 ε-晶体蛋白，表明这些蛋白质属于同一基因家族。最近，我们发现针对 3α-羟甾类脱氢酶的单克隆抗体也在大鼠肺、肾和睾丸中识别出多种抗原相关蛋白。使用这些单克隆抗体作为探针进一步筛选肝、肺和肾 cDNA 文库，分离出另外五个编码与大鼠肝 3α-羟甾类脱氢酶具有高度结构同源性的蛋白质的不同 cDNA。
