The activity and biosynthesis of cholesterol side-chain cleavage enzyme in cultured immature pig testis cells.

An IgG fraction from antiserum raised against cholesterol side-chain cleavage cytochrome P-450 (cytochrome P-450scc) purified from bovine adrenocortical mitochondria cross-reacted with immature pig testis cytochrome P-450scc in an Ouchterlony double diffusion system. This property of the IgG fraction was utilized for the immunoisolation of cytochrome P-450scc of immature pig testis cells in culture. The molecular weight of the immunoisolate from [35S]methionine-labeled pig testis Leydig cells was similar to that of purified bovine adrenocortical cytochrome P-450scc (49 000). The testis iron-sulfur protein similarly immunoisolated using an IgG fraction from antiserum raised against adrenodoxin purified from bovine adrenocortical mitochondria was also of molecular weight similar to that of adrenodoxin (13 000). The rates of synthesis of cytochrome P-450scc and testis iron-sulfur protein in immature pig testis cells in culture, when incubated with hCG (100 mU/ml) for 48 h, were 3- and 6-fold greater, respectively, than those in cells incubated in the absence of hCG. This result is suggestive that the synthesis of cytochrome P-450scc and testis iron-sulfur protein of immature pig testis tissue is stimulated by gonadotropin.