EFFECT OF TUBULIN IN PMCA ACTIVITY DEPENDS ON LIPID COMPOSITION WHERE THE ENZYME IS IMMERSED.

MONESTEROLO N.; CAMPETELLI AN; AMAIDEN MR; SANTANDER VS; PREVITALI G; CASALE CH.

Puerto Madryn

Congreso; SAIB 2010; 2010

In previous work we demostrated that acetylated tubulin forms a complex with PMCA (Ca2+-ATPase) and the formation of the complex in vivo inhibits the enzimatic activity. We recently demonstrated that the effect of tubulin on PMCA activity is depends on the environment in which both proteins are immersed. The reconstitution of the PMCA in liposomes and the subsequent addition of tubulin caused the activation of the PMCA. In this work we study the effect of tubulin on the PMCA activity reconstituted in different lipids. For this proposes PMCA was purified from rat brain and reconstituted in liposomes with diacylglycerol (DAG), phosphatidic acid (PA) or phosphatidylcholine (PC). Results shown that tubulin is able to activate PMCA independently of the tubulin concentration when the enzyme was reconstituted in BE and PA. However, tubulin affect the enzyme activity in a dose dependent manner when the reconstitution was done in DAG or PC. Low tubulin concentrations (below 25 µg/ml) activates PMCA more than two times, while higher concentrations inhibited the enzyme. These results indicate that the effect of tubulin on the PMCA activity is depends on the lipid composition in which the enzyme is immersed and the tubulin concentration.