Role of albumin as a fatty acid carrier for biosynthesis of lens lipids.

Although serum albumin is the major protein component of the aqueous humor and vitreous humor, its possible physiological role(s) in lens metabolism has not yet been determined. BODIPY fatty acid, a fluorescent analogue of a C(12) long chain fatty acid, was bound to serum albumin, then incubated with lenses in culture. After various times of incubation, the lenses were homogenized, lipids extracted, and the extracted lipids resolved by thin layer chromatography. Fluorescence analyses demonstrated that the BODIPY fatty acid--albumin complex was translocated into the lens, where the BODIPY fatty acid was incorporated in a time dependent manner into numerous lipids, including phosphatidylcholine, phosphatidylethanolamine, and sphingomyelin. Together, the results strongly suggest that serum albumin in the aqueous humor and/or vitreous humor facilitates the translocation of long chain fatty acids into the lens, where they are used for the biosynthesis of lens lipids.