title: Calcium-dependent association of 33 kDa protein in polymorphonuclear leukocytes with phospholipid liposomes containing phosphatidylserine or cardiolipin.
abstract: The effects of lipids and Ca2+ on the association of cytoplasmic proteins of polymorphonuclear leukocytes (PMN) with dipalmitoylphosphatidylcholine liposomes containing phosphatidylserine (PS) or cardiolipin (CL) were examined. In the presence of Ca2+, a cytoplasmic protein (33 kDa) of PMN was found to be a major component that bound to these liposome membranes. The maximum association with the liposomes was obtained at the molecular concentration of 25% CL and 50% PS; the required concentrations of Ca2+ were in the nanomolar and micromolar ranges for CL and PS, respectively. The liposome-associated 33 kDa protein was released from liposomes by an addition of EGTA. These results suggest that the 33 kDa protein reversibly associates to the cytoplasmic surface of PMN plasma membranes where PS localizes depending on a small change in intracellular concentration of free Ca2+.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002308:Cardiolipins / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004533:Egtazic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D008081:Liposomes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism*; D010718:Phosphatidylserines / Q000494:pharmacology*; D051381:Rats
chemical_list: D002308:Cardiolipins; D008081:Liposomes; D008565:Membrane Proteins; D010718:Phosphatidylserines; D004533:Egtazic Acid; D002118:Calcium