Effects of polyene cholesterol-binding antibiotics on the binding and removal of cholesterol from bovine adrenocortical cytochrome P-450SCC: difference in properties of the membrane-bound and membrane-free cytochrome.

The polyene cholesterol-binding antibiotics filipin and amphotericin B inhibited the binding of cholesterol to steroid-free, soluble adrenocortical cytochrome P-450SCC. In mitochondria-bound cytochrome P-450SCC, cholesterol was not extracted by filipin, whereas filipin was able to react with cholesterol bound to purified soluble cytochrome P-450SCC. Based on these results we conclude that the cholesterol-binding site of membrane-bound cytochrome P-450SCC is masked by membrane structures.