In vitro cytochrome b5 binding to microsomal membranes: functional and non-functional levels.

A comparison of the apparent level of cytochrome binding b5 to liver and kidney microsomes was undertaken comparing values obtained by dithionite vs. NADH reduction. Significant differences both in the extent and specificity of binding to microsomes from liver and kidney were found. These results suggest careful consideration of the apparent binding site availability based on means of reduction is in order.