Rainbow trout cytochrome P‐450c17 (17α‐hydroxylase/17,20‐lyase) cDNA cloning, enzymatic properties and temporal pattern of ovarian P‐450c17 mRNA expression during oogenesis

A cDNA clone encoding cytochrome P-450c17 (17α-hydroxylase/17,20-lyase) was isolated from a rainbow trout ovarian follicle cDNA library. The cDNA contained an open reading frame of 1,542 nucleotides encoding a protein of 514 amino acid residues. The amino acid sequence of trout P-450c17 shows a much greater homology with chicken P-450c17 than with that of human, bovine and rat. The trout P-450c17 expressed in non-steroidogenic mammalian COS-1 cells showed both 17α-hydroxylase and 17,20-lyase activities. The cDNA only hybridized to a single species or mRNA (2.4 kb) isolated from rainbow trout ovaries; the 2.4 kb transcripts were abundant in trout ovaries during the later stages of oogenesis.