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

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

Puerto Madryn

Congreso; 46 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2010

In previous work we demonstrated that acetylated tubulin forms acomplex with PMCA (Ca2+-ATPase) and the formation of thecomplex in vivo inhibits the enzimatic activity. We recentlydemonstrated that the effect of tubulin on PMCA activity dependson the environment in which both proteins are immersed. Thereconstitution of the PMCA in liposomes and the subsequentaddition of tubulin caused the activation of the PMCA. In this workwe study the effect of tubulin on the PMCA activity reconstituted indifferent lipids. For this proposes PMCA was purified from rat brainand reconstituted in liposomes with diacylglycerol (DAG),phosphatidic acid (PA) or phosphatidylcholine (PC). Results shownthat tubulin is able to activate PMCA independently of the tubulinconcentration when the enzyme was reconstituted in BE and PA.However, tubulin affect the enzyme activity in a dose dependentmanner when the reconstitution was done in DAG or PC. Lowtubulin concentrations (below 25 μg/ml) activates PMCA more thantwo times, while higher concentrations inhibited the enzyme. Theseresults indicate that the effect of tubulin on the PMCA activitydepends on the lipid composition in which the enzyme is immersedand the tubulin concentration.