Role of lipidic environment in the tubulin regulation of plasma membrane Ca2+-ATPase.

MONESTEROLO N.E; CAMPETELLI A.N; AMAIDEN MR; SANTANDER VS; PREVITALI G; CASALE C. H.

Tucuman

Congreso; SAIB 2009; 2009

SAIB

Our working group demonstrated that tubulin interacts with some members of the family of P-ATPase, (Na+,K+ ATPase, H+ ATPase and Ca2+ ATPase) in different systems. The interactions with tubulin modify the enzymatic activity of these P-ATPases. In this paper we focus on the behavior of PMCA (Ca2+ ATPase) in the presence of acetylated tubulin in different preparations. Here we show that in COS and CAD cells and human erythrocyte intracellular calcium concentration (estimated by Fura 2-AM) decreased with the addition of ethanol, in addition a decrease in the formation of the complex acetylated tubulin/PMCA was observed. Recent experiments suggest that the formation of the complex would be due to a direct interaction of PMCA/tubulina and that the activity-dependent PMCA lipids surrounding the enzyme, this hypothesis is supported by the following results: 1 -preparations of purified PMCA reconstituted into liposomes and subsequent addition of tubulin leads to activation of PMCA. 2 -the increase in PMCA activity depends on the lipids used in reconstitution, and 3 -the alteration of lipid membranes of rat brain produced by treatment with PLC modifies the effect of exogenous tubulin on the activity of PMCA, with an activation of the enzyme. These results show that the effect of tubulin on PMCA activity depends on the lipidic composition where the enzyme is immersed.