A photo‐reactive derivative of ganglioside GM1 specifically cross‐links VIP21‐caveolin on the cell surface

Abstract

Previous studies have shown that sphingolipids may be enriched in caveolae, plasmalemmal invaginations implicated in endocytosis and signal transduction. We synthesised a radiolabeled derivative of ganglioside GM1 bearing a photo‐reactive cross‐linker at the end of its acyl chain. After insertion in the plasma membrane of cultured A431 or MDCK cells and photoactivation, the main protein cross‐linked by the GM1 derivative was VIP21‐caveolin, an essential structural component of caveolae. This result shows close proximity between GM1 molecules and VIP21‐caveolin in the caveolar membrane and strongly implicates sphingolipid segregation in the biogenesis of caveolae.