Phospholipid methylation and the transmission of biological signals through membranes

Enzymatic methylation of phosphotidylethanolamine (PE) to form phosphatidylcholine (PC) is associated with translocation of the lipid from the inner cell membrane (PE) to the outer membrane (PC), a concomitant decrease in membrane viscosity, and in some cases, activation of phospholipase A and release of arachidonic acid. Changes in phospholipid methylation are induced by a variety of ligands upon interaction with their specific receptors. In each case stimulation of phospholipid methylation appears to contribute to the propagation of the particular physiological response (e.g., activation of adenylate cyclase in rat reticulocytes; release of histamine by mast cells; chemotactic movement of neutrophils; mitogenesis of lymphocytes). Thus, receptor-mediated changes in phospholipid methylation and membrane fluidity may represent a general mechanism leading to a specific cellular response.