The distribution of cholesterol and phospholipid composition in submitochondrial membranes from bovine adrenal cortex: fundamental studies of steroidogenic mitochondria.

The cholesterol contents and phospholipid compositions of mitochondria, microsomes and submitochondrial membranes from bovine adrenal cortex have been analyzed quantitatively. From our results, the following cholesterol contents were obtained: mitochondria, 6.2 +/- 0.9 mol %; microsomes, 18.4 +/- 2.8 mol %; mitochondrial inner membrane, 2.8 +/- 0.6 mol %; and mitochondrial outer membrane, 8.3 +/- 1.3 mol %. In addition, the phospholipid compositions of the mitochondrial inner and outer membranes were determined for the first time. Cardiolipin was found to be enriched in the inner membrane, whereas phosphatidylinositol was richer in the outer membrane. The general features of phospholipid compositions in the submitochondrial membranes resembled that of rat liver mitochondria.