Polyphosphoinositides Are Present in Plasma Membranes Isolated from Fusogenic Carrot Cells

摘要

Fusogenic carrot cells grown in suspension culture were labeled 12 hours with myo-(2-tritium) inositol. Plasma membranes were isolated from the prelabeled fusogenic carrot cells by both aqueous polymer two-phase partitioning and Renografin density gradients. With both methods, the plasma membrane-enriched fractions, as identified by marker enzymes, were enriched in tritium inositol-labeled phosphatidylinositol monophosphate (PIP) and phosphatidylinositol biphosphate (PIP2). An additional tritium inositol-labeled lipid, lysophosphatidylinositol monophosphate, which migrated between PIP and PIP2 on thin layer plates, was in contrast to lysophosphatidylinositol which is found primarily in the lower phase, microsomal/mitochrondrial-rich fraction.