Isolation from haemolysate of a proteinaceous inhibition of the red cell Ca2+-pump ATPase. Its action on the kinetics of the enzyme.
The purification to apparent homogeneity of a small protein from the cytosol of human red cells is described. The procedure consists of a combination of anion-exchange-chromatography, ultrafiltration, (NH4)2SO4- and heat-precipitation. The resulting protein is a potent inhibitor of (Ca2+ + Mg2+)-ATPase of erythrocyte membranes and of Ca2+-uptake into inside-out vesicles. Membrane (Na+ + K+)-ATPase is not affected by the inhibitor. The peptide migrates as a single band in SDS gels. Its apparent molecular weight is 19,000. It causes inhibition of the Ca2+-pump by decreasing Ca2+-affinity at all calmodulin concentrations.
D001798:Blood Proteins / Q000302:isolation & purification*; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000097:blood*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors* / Q000097:blood; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000032:analysis; D004912:Erythrocytes / Q000032:analysis*; D006461:Hemolysis; D006358:Hot Temperature; D006801:Humans; D007700:Kinetics; D008970:Molecular Weight; D014462:Ultrafiltration
D001798:Blood Proteins; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D002118:Calcium