ROLE OF LIPIDIC ENVIRONMENT IN THE TUBULIN REGULATION OF PMCA

MONESTEROLO NE; CAMPETELLI AN; AMAIDEN MR; SANTANDER VS; ARCE CA; CASALE CH

San Miguel de Tucuman

Congreso; SAIB - th 45 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2009

Our working group demonstrated that tubulin interacts with somemembers of the family of P-ATPase, (Na+,K+-ATPase, H+-ATPaseand Ca2+ -ATPase) in different systems. The interactions withtubulin modify the enzymatic activity of these P-ATPases. In thispaper we focus on the behavior of PMCA (Ca2+-ATPase) in thepresence of acetylated tubulin in different preparations. Here weshow that in COS and CAD cells and human erythrocyteintracellular calcium concentration (estimated by Fura 2-AM)decreased with the addition of ethanol, in addition a decrease in theformation of the complex acetylated tubulin/PMCA was observed.Recent experiments suggest that the formation of the complexwould be due to a direct interaction of PMCA/tubulina and that theactivity-dependent PMCA lipids surrounding the enzyme, thishypothesis is supported by the following results: 1 -preparations ofpurified PMCA reconstituted into liposomes and subsequentaddition of tubulin leads to activation of PMCA. 2 -the increase inPMCA activity depends on the lipids used in reconstitution, and 3 -the alteration of lipid membranes of rat brain produced by treatmentwith PLC modifies the effect of exogenous tubulin on the activity ofPMCA, with an activation of the enzyme. These results show thatthe effect of tubulin on PMCA activity depends on the lipidiccomposition where the enzyme is immersed.