PHOSPHOINOSITIDES AS SPATIAL REGULATORS OF MEMBRANE TRAFFIC

Inositol phospholipids are a focus of renewed interest with the discov ery of their unanticipated pivotal roles in membrane trafficking event s, Reversible phosphorylation of phosphatidylinositol generates spatia lly localized signals on membranes that recruit or activate proteins e ssential for cell membrane budding, fission and fusion. Recent advance s have taken place in the characterization of lipid kinases and phosph oinositide-regulated effector proteins, and in the elucidation of phos pholipase D mediated mechanisms involving ADP ribosylation factor and Rho family proteins, The roles played by phosphoinositides in aspects of secretory granule formation, fusion and endocytosis indicate the im portance of phosphorylated lipids for neurotransmitter release.