Activation of PMCA by calmodulin or ethanol in plasma membrane vesicles from rat brain involves dissociation of the acetylated tubulin/PMCA complex.
We have recently shown that acetylated tubulin interacts with plasma membrane Na(+),K(+)-ATPase and inhibits its enzyme activity in several types of cells. H(+)-ATPase of Saccharomyces cerevisiae is similarly inhibited by interaction with acetylated tubulin. The activities of both these ATPases are restored upon dissociation of the acetylated tubulin/ATPase complex. Here, we report that in plasma membrane vesicles isolated from brain synaptosomes, another P-type ATPase, plasma membrane Ca(2+)-ATPase (PMCA), undergoes enzyme activity regulation by its association/dissociation with acetylated tubulin. The presence of acetylated tubulin/PMCA complex in membrane vesicles was demonstrated by analyzing the behavior of acetylated tubulin in a detergent partition, and by immunoprecipitation experiments. PMCA is known to be stimulated by ethanol and calmodulin at physiological concentrations. We found that treatment of plasma membrane vesicles with these reagents induced dissociation of the complex, with a concomitant restoration of enzyme activity. Conversely, incubation of vesicles with exogenous tubulin induced the association of acetylated tubulin with PMCA, and the inhibition of enzyme activity. These findings indicate that activation of synaptosomal PMCA by ethanol and calmodulin involves dissociation of the acetylated tubulin/PMCA complex. This regulatory mechanism was shown to also operate in living cells.
Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Argentina.
Noelia E
NE
Monesterolo
Verónica S
VS
Santander
Alexis N
AN
Campetelli
Carlos A
CA
Arce
Héctor S
HS
Barra
Cesar H
CH
Casale
D000107:Acetylation; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002147:Calmodulin / Q000494:pharmacology*; D002462:Cell Membrane / Q000201:enzymology*; D022162:Cytoplasmic Vesicles / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation; D000431:Ethanol / Q000494:pharmacology*; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000378:metabolism*; D051381:Rats; D014404:Tubulin / Q000378:metabolism* / Q000494:pharmacology; D050257:Tubulin Modulators / Q000494:pharmacology
D002147:Calmodulin; D014404:Tubulin; D050257:Tubulin Modulators; D000431:Ethanol; D053499:Plasma Membrane Calcium-Transporting ATPases