Evidence for the presence in smooth muscle of two types of Ca2+-transport ATPase.
Membrane fractions prepared from smooth muscle of the pig stomach (antral part) contain two Ca2+-dependent phosphoprotein intermediates belonging to different Ca2+-transport ATPases. These alkali-labile phosphoproteins can be separated by electrophoresis in acid medium. The 130 kDa phosphoprotein resembles a corresponding protein in the erythrocyte membrane, whereas the 100 kDa protein resembles that of the Ca2+-transport ATPase in sarcoplasmic reticulum from skeletal muscle. These resemblances are expressed in terms of Mr, reaction to La3+ and in a similar proteolytic degradation pattern. The presence of the calmodulin-stimulated ATPase in mixed membranes from smooth muscle is confirmed by its binding of calmodulin and antibodies against erythrocyte Ca2+-transport ATPase, whereas such binding does not occur with proteins present in the presumed endoplasmic reticulum from smooth muscle.
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000276:immunology / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism; D002462:Cell Membrane / Q000201:enzymology; D004591:Electrophoresis, Polyacrylamide Gel; D007136:Immunoglobulins / Q000276:immunology; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism*; D007811:Lanthanum / Q000494:pharmacology; D009130:Muscle, Smooth / Q000201:enzymology*; D010766:Phosphorylation; D013347:Subcellular Fractions / Q000201:enzymology; D013552:Swine; D014357:Trypsin
D002147:Calmodulin; D007136:Immunoglobulins; D007527:Isoenzymes; D007811:Lanthanum; D014357:Trypsin; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases