title: Protein-stimulated enrichment of human platelet membranes in linoleylphosphatidylcholines. Effect upon adenylate cyclase and fluidity.
abstract: In order to study the effect of linoleyl enrichment of platelet membranes upon adenylate cyclase activity and membrane fluidity, manipulations of platelet phospholipids are carried out with phosphatidylcholine-loaded high-density lipoproteins (HDL) or phospholipid-exchange protein and phospholipid-cholesterol mixed vesicles. Incubation with HDL does not appear to be valuable for this purpose. On the other hand, phospholipid-exchange protein and mixed vesicles can be used successfully. Phospholipid-exchange protein stimulated 3-fold the spontaneous exchange of 2-linoleylphosphatidylcholine between the vesicles and the platelets. Linoleyl enrichment of platelets by dilinoleylphosphatidylcholine is about 25% and by 2-linoleylphosphatidylcholine is about 45-50%. The unsaturation index remains constant when the enrichment is performed using dilinoleylphosphatidylcholine but it increases with 2-linoleylphosphatidylcholine. Basal and prostaglandin E1-stimulated adenylate cyclase activities are not modified by dilinoleylphosphatidylcholine, while they increase significantly in the case of 2-linoleylphosphatidylcholine. There is no significant variation in diphenyl hexatriene fluorescence polarization parameters, either with dilinoleylphosphatidylcholine or with 2-linoleylphosphatidylcholine.
mesh_terms: D000262:Adenylyl Cyclases / Q000097:blood*; D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D006801:Humans; D008041:Linoleic Acids / Q000097:blood / Q000138:chemical synthesis; D008075:Lipoproteins, HDL / Q000097:blood*; D008081:Liposomes; D008560:Membrane Fluidity; D010713:Phosphatidylcholines / Q000097:blood*
chemical_list: D008041:Linoleic Acids; D008075:Lipoproteins, HDL; D008081:Liposomes; D010713:Phosphatidylcholines; C002448:1,2-linoleoylphosphatidylcholine; D000262:Adenylyl Cyclases