A cDNA clone encoding 3β-hydroxysteroid dehydrogenase/Δ5-4-isomerase (3β-HSD) was isolated from a cDNA library of rainbow trout ovarian thecal cells. Southern hybridization analysis of trout genomic DNA with the cDNA suggested the presence of a single gene encoding 3β-HSD in the rainbow trout showing a total genomic size of less than 4 kilobases (kb). The cDNA hybridized to a single species of mRNA isolated from rainbow trout ovaries; the 1.4 kb transcripts were most abundant in trout ovaries during the later stages of oogenesis. The trout 3β-HSD expressed in non-steroidogenic monkey kidney tumor (COS-1) cells showed a unique enzymatic 3β-HSD activity. Dehydroepiandrosterone was a more favoral substrate of the trout 3β-HSD than 17α-hydroxypregnenolone. Interestingly, the trout 3β-HSD expressed in COS-1 cells exhibited minimal ability to convert pregnenolone to progesterone. © 1994.
Sakai, N., Tanaka, M., Takahashi, M., Fukada, S., Ian Mason, J., & Nagahama, Y. (1994). Ovarian 3,β-hydroxysteroid dehydrogenase/Δ5-4-isomerase of rainbow trout: Its cDNA cloning and properties of the enzyme expressed in a mammalian cell. FEBS Letters, 350(2–3), 309–313. https://doi.org/10.1016/0014-5793(94)00795-0