RGD Reference Report - 3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase expression in rat and characterization of the testis isoform. - Rat Genome Database

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3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase expression in rat and characterization of the testis isoform.

Authors: Lorence, MC  Naville, D  Graham-Lorence, SE  Mack, SO  Murry, BA  Trant, JM  Mason, JI 
Citation: Lorence MC, etal., Mol Cell Endocrinol. 1991 Sep;80(1-3):21-31.
RGD ID: 1625116
Pubmed: (View Article at PubMed) PMID:1955079

The isolation, cloning and expression of a DNA insert complementary to mRNA encoding rat testis 3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase (3 beta-HSD) is reported. The insert contains an open reading frame encoding a protein of 373 amino acids, which exhibits 73% and 78% identity to the cDNA encoding the human placental form at the amino acid and nucleotide levels respectively. Northern blot analysis of total RNA of rat tissues using as probe a specific radiolabeled cDNA insert encoding rat testis 3 beta-HSD demonstrated high levels of 1.6 kb mRNA species in ovary, adrenal and Leydig tumor, with lower but detectable message in testis and adult male liver, while the probe also hybridized to a 2.1 kb mRNA species in liver. The cDNA was inserted into a modified pCMV vector and expressed in COS-1 monkey kidney tumor cells. The expressed protein was similar in size to 3 beta-HSD present in H540 Leydig tumor cell homogenate and human placental microsomal 3 beta-HSD, as detected by immunoblot analysis, and catalyzed the conversion of pregnenolone to progesterone, 17 alpha-hydroxypregnenolone to 17 alpha-hydroxyprogesterone, and dehydroepiandrosterone to androstenedione. Transfected COS cell homogenates, supplemented with NAD+, but not NADP+, converted pregnenolone to progesterone and dehydroepiandrosterone to androstenedione with apparent Km values of 0.13 and 0.09 microM, respectively. Immunoblot analysis of various rat tissues using a polyclonal antibody directed against human placental 3 beta-HSD, in addition to immunoreactivity in the adrenal and testis, demonstrated immunoreactive 3 beta-HSD protein in adult male liver, but not in adult female or fetal liver. We conclude that while one gene product is highly expressed in testicular Leydig cells, and probably adrenal and ovary, accounting for their 3 beta-HSD content, a 3 beta-HSD is also expressed in liver in a sex-specific manner.

Annotation

Gene Ontology Annotations    

Biological Process

Molecular Function

Objects Annotated

Genes (Rattus norvegicus)
Hsd3b1  (hydroxy-delta-5-steroid dehydrogenase, 3 beta- and steroid delta-isomerase 1)


Additional Information