Possible steroid binding site common to adrenal cytochrome P-450scc and prostatic steroid binding protein

By searching the entire PIR-protein-sequence data base, we have found that a dodecapeptide sequence in bovine adrenal cytochrome P-450scc is closely related to that in rat prostatic steroid binding protein. The two proteins belong to unrelated protein families, but both have steroids as substrates or ligands. Thus, the dodecapeptides may be important for substrate/ligand recognition in the individual proteins.