title: Characterization of a Polyphosphoinositide Phospholipase C from the Plasma Membrane of Avena sativa.
abstract: A phosphoinositide-specific phospholipase C activity was identified in oat root (Avena sativa, cv Victory) plasma membranes purified by separation in an aqueous two-phase polymer system. The enzyme is highly active toward inositol phospholipids but only minimally active toward phosphatidylethanolamine and phosphatidylcholine. Activity approaches maximal levels at 200 micromolar phosphatidylinositol 4-phosphate (PIP) and is highly dependent on calcium; it is inhibited by 1 millimolar EGTA and is activated by calcium with an apparent activation constant of 2 micromolar. At 10 micromolar calcium and 200 micromolar inositol phospholipid, the enzyme is specific for phosphatidylinositol 4,5-bisphosphate (PIP(2)) and PIP, which are hydrolyzed at 10 and 4 times, respectively, the rate of phosphatidylinositol (PI) hydrolysis. The principle water soluble products of hydrolysis, as determined by high performance liquid chromatography, are inositol 1,4,5-trisphosphate from PIP(2), inositol 1,4-bisphosphate from PIP, and inositol phosphate from PI.
authors: Department of Molecular and Cell Biology U-125 University of Connecticut, Storrs, Connecticut 06269-3125.
authors: B F
authors: BF
authors: Tate
authors: G E
authors: GE
authors: Schaller
authors: M R
authors: MR
authors: Sussman
authors: R C
authors: RC
authors: Crain