title: Vesiculation of platelet plasma membranes. Dilauroylglycerophosphocholine-induced shedding of a platelet plasma membrane fraction enriched in acetylcholinesterase activity.
abstract: Incubation of washed rabbit platelets with suspensions of dilauroylglycerophosphocholine resulted in the shedding of vesicles without causing any appreciable leakage of cytoplasmic marker (lactate dehydrogenase) or organelle marker [( 14C]serotonin). The response was dependent on incubation time, concentration of dilauroylglycerophosphocholine and reaction temperature. Vesicles were separated from platelets and exogenous dilauroylglycerophosphocholine by a series of centrifugation steps. An average diameter of vesicles was 100-200 nm on scanning electron microscopy. Vesicles were enriched 5-fold in plasma membrane marker enzyme, acetylcholinesterase, whereas specific activities of lactate dehydrogenase and intracellular membrane marker enzyme, NADH-cytochrome c reductase were decreased in vesicles. Protein analysis by SDS-polyacrylamide gel electrophoresis showed that actin and actin-binding protein were present, while myosin was barely detectable in vesicles. Vesicles contained all phospholipid species of intact platelets and cholesterol but almost 50% of phospholipids in vesicles was dilauroylglycerophosphocholine. The phospholipid to protein ratio in vesicles was about 6.5-times higher than in intact platelets.
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D001792:Blood Platelets / Q000187:drug effects / Q000648:ultrastructure*; D002458:Cell Fractionation / Q000379:methods; D002462:Cell Membrane / Q000201:enzymology / Q000648:ultrastructure*; D002498:Centrifugation; D002784:Cholesterol / Q000097:blood; D008563:Membrane Lipids / Q000097:blood; D008565:Membrane Proteins / Q000097:blood; D008855:Microscopy, Electron, Scanning; D010713:Phosphatidylcholines / Q000494:pharmacology*; D010743:Phospholipids / Q000097:blood; D011817:Rabbits
chemical_list: D008563:Membrane Lipids; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D010743:Phospholipids; C015153:1,2-dilauroylphosphatidylcholine; D002784:Cholesterol; D000110:Acetylcholinesterase