Influence of phospholipid structure on sterol efflux induced by albumin-phospholipid complexes.

Sterol release from strain L fibroblasts was measured in serum-free medium supplemented with delipidated human serum albumin and various phospholipids. The sterol molecule appears to preferentially interact with the sn-2-acyl chain of the phospholipid. The carbonyl oxygen of the phospholipid acyl ester linkage is not required for sterol-phospholipid interactions, while the phosphate and choline groups are required. In the presence of the human serum albumin-phospholipid complex, phospholipids containing trans-acyl groups are significantly more effective at removing cellular sterol than the corresponding cis-acyl group.