New role of glycosaminoglycans on the plasma membrane proposed by their interaction with phosphatidylcholine.

Glycosaminoglycan side chains of membrane proteoglycans have been claimed to be located at the outermost layer of the glycocalyx surrounding the cell. In this study measurements by surface plasmon resonance and solid-phase assay have shown that both chondroitin sulfate and keratan sulfate but not heparin associate with phosphatidylcholine under physiological conditions. Spectrophotometric measurements also showed that chondroitin sulfate restricts the lateral diffusion of phosphatidylcholine in liposomes. These findings indicate that chondroitin sulfate and/or keratan sulfate chains of membrane proteoglycans crouch on the surface of the membrane while heparan sulfate chains stretch outward from the membrane surface as postulated traditionally.