INTERACTIONS OF LIPIDS WITH A MEMBRANE STRUCTURAL PROTEIN FROM MYELIN

A water-soluble, delipidated membrane protein from bovine brain myelin combines with anionic lipids to form insoluble complexes. The minimal amount of phosphatidylserine, phosphatidylinositol, cerebroside sulfate, and oleic acid required to completely precipitate the protein corresponds to 39 mole % of the total basic amino acid groups in the protein. Complexes precipitate optimally near neutrality and are stabilized by divalent cations. Nonionic lipids (cholesterol and cerebroside) and lecithin form nonprecipitating complexes with the protein which can be demonstrated by centrifugation in sucrose density gradients. These lipids also bind to protein-anionic lipid complexes. Succinylation of the protein greatly reduces interaction with lipids and abolishes the capacity to form insoluble complexes. These observations are discussed with respect to the structural role which different kinds of lipids might assume in myelin. © 1969, American Chemical Society. All rights reserved.