title: The function of glycosyl phosphoinositides in hormone action.
abstract: The molecular events involved in the cellular actions of insulin remain unexplained. Some of the acute actions of the hormone may be due to the intracellular generation of a chemical substance which modulates certain enzyme activities. Such an enzyme-modulating substance has been identified as an inositol phosphate-glycan, produced by the insulin-sensitive hydrolysis of a glycosyl-phosphatidylinositol (glycosyl-PtdIns) precursor. This precursor glycolipid is structurally similar to the glycosyl-phosphoinositide membrane protein anchor. The exposure of fat, liver or muscle cells to insulin results in the hydrolysis of glycosyl-PtdIns, giving rise to the inositol phosphate glycan and diacylglycerol. This hydrolysis reaction is catalysed by a glycosyl-PtdIns-specific phospholipase C. This enzyme has been characterized and purified from a plasma membrane fraction of liver. This reaction also results in the acute release of certain glycosyl-PtdIns-anchored proteins from the cell surface. Elucidation of the functional role of glycosyl-phosphoinositides in the generation of second messengers or the release of proteins may provide further insights into the pleiotropic nature of insulin action.
authors.affiliation: Laboratory of Biochemical Endocrinology, Rockefeller University, New York 10021.
authors.forename: A R
authors.initials: AR
authors.lastname: Saltiel
authors.forename: D G
authors.initials: DG
authors.lastname: Osterman
authors.forename: J C
authors.initials: JC
authors.lastname: Darnell
authors.forename: L R
authors.initials: LR
authors.lastname: Sorbara-Cazan
authors.forename: B L
authors.initials: BL
authors.lastname: Chan
authors.forename: M G
authors.initials: MG
authors.lastname: Low
authors.forename: P
authors.initials: P
authors.lastname: Cuatrecasas
mesh_terms: D000818:Animals; D002468:Cell Physiological Phenomena; D006017:Glycolipids / Q000502:physiology*; D007328:Insulin / Q000502:physiology*; D010716:Phosphatidylinositols / Q000502:physiology*
chemical_list: D006017:Glycolipids; D007328:Insulin; D010716:Phosphatidylinositols