Distribution of plasma membrane Ca(2+)-ATPase and inositol 1,4,5-trisphosphate receptor in human platelet membranes.
Human platelet plasma membranes were prepared by the glycerol lysis method of Harmon et al. [Harmon JT. Greco NJ. Jamieson GA. (1992) Isolation of human platelet plasma membranes by glycerol lysis. Meth. Enzymol., 215, 32-36]. The membranes were observed to contain a Ca(2+)-ATPase with different properties than those of internal membranes. The specific activity of Ca(2+)-ATPase was lower in plasma membranes (10-40 nmol ATP hydrolyzed/min/mg), but the ATPase was less sensitive to thapsigargin (41% inhibition at 500 nM) and more sensitive to vanadate (50% inhibition at 4 microM) than the Ca(2+)-ATPase in internal platelet membranes. The plasma membranes contained a Ca(2+)-ATPase detectable by monoclonal and polyclonal antibodies against erythrocyte Ca(2+)-ATPase that had a molecular mass of 144 kD. However, an anti-peptide antibody against an N-terminal sequence of the inositol 1,4,5-trisphosphate receptor recognized this protein in internal membranes, but not plasma membranes.
Dean
W L
WL
Department of Biochemistry, University of Louisville School of Medicine, Kentucky, USA.
Quinton
T M
TM
D001792:Blood Platelets / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000097:blood* / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D003429:Cross Reactions; D004910:Erythrocyte Membrane / Q000378:metabolism; D006801:Humans; D007120:Immunochemistry; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000097:blood; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008970:Molecular Weight; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D018160:Receptors, Cytoplasmic and Nuclear; D013729:Terpenes; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D000252:Calcium-Transporting ATPases