Freely turning over palmitate in erythrocyte membrane proteins is not responsible for the anchoring of lipid rafts to the spectrin skeleton: a study with bio-orthogonal chemical probes.
Ankyrin is a peripheral membrane protein that mediates the attachment of the erythrocyte membrane skeleton to the plasma membrane. We show that [3H]palmitic acid is incorporated into ankyrin in vivo. The majority of the 3H-labeled fatty acid is covalently bound to the polypeptide, as it cannot be removed by strong detergents or by chloroform/methanol extraction but is labile to alkaline hydrolysis. The binding of fatty acid occurs predominantly after the assembly of ankyrin onto the membrane skeleton, since it continues when protein synthesis is inhibited with emetine. Fatty acid acylation of ankyrin is constitutive in erythroid cells throughout chicken embryo development. It also occurs in mature avian and mammalian erythrocytes suggesting that the fatty acid bound to ankyrin turns over more rapidly than the polypeptide. Fatty acid acylation of assembled ankyrin may modulate the interaction of ankyrin with the plasma membrane. It may also provide a mechanism by which the membrane skeleton influences the organization of the lipid bilayer.