The inhibitor peptide of the mitochondrial F1.F0-ATPase interacts with calmodulin and stimulates the calmodulin-dependent Ca2+-ATPase of erythrocytes.
The binding of calmodulin to the mitochondrial F1.F0-ATPase has been studied. [125I]Iodoazidocalmodulin binds to the epsilon-subunit and to the endogeneous ATPase inhibitor peptide in a Ca2+-dependent reaction. The effect of the mitochondrial ATPase inhibitor peptide on the purified Ca2+-ATPase of erythrocytes has also been analyzed. The inhibitor peptide stimulates the ATPase when pre-incubated with the enzyme. The activation of the Ca2+-ATPase by calmodulin is not influenced by the inhibitor peptide, indicating that the two mechanisms of activation are different. These in vitro effects of the two regulatory proteins may reflect a common origin of the two ATPases considered and/or of the regulatory proteins.
Schwerzmann
K
K
Müller
M
M
Carafoli
E
E
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors*; D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D000252:Calcium-Transporting ATPases / Q000097:blood*; D002147:Calmodulin / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D004789:Enzyme Activation / Q000187:drug effects; D004912:Erythrocytes / Q000201:enzymology*; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008928:Mitochondria / Q000201:enzymology*; D011485:Protein Binding / Q000187:drug effects; D011506:Proteins / Q000378:metabolism / Q000494:pharmacology*; D006180:Proton-Translocating ATPases; D051381:Rats; D000097795:ATPase Inhibitory Protein
D000251:Adenosine Triphosphatases; D000252:Calcium-Transporting ATPases; D002147:Calmodulin; D007093:Imidazoles; D011506:Proteins; D006180:Proton-Translocating ATPases; D000097795:ATPase Inhibitory Protein; C031938:calmidazolium