Clustering in coated vesicles of polyunsaturated phospholipids segregated from plasma and Golgi membranes of adrenocortical cells.

In bovine adrenocortical cells, the fatty acyl chains of the phospholipids have been identified in the membranes of the different cell compartments: plasma membranes, Golgi complex and coated vesicle membranes. An increase in the total number of unsaturation in the fatty acid is demonstrated in the coated vesicle membranes as compared with the plasma and Golgi membranes. Furthermore, it appears that phosphatidylcholine and phosphatidylethanolamine are both enriched in polyunsaturated fatty acyl chains, namely arachidonic and adrenic acids in both types of coated vesicles. Only two of the fatty acids are characteristic of Golgi complex and small coated vesicles, 22:5 (n-6) in PC and 22:6 (n-3) in PE, suggesting that the SCV could originate from the Golgi stacks. A high value of the ratio 22:5 (n-3)/22:6 (n-3) is observed which is, as far as we know, characteristic of adrenal cells.