Partial characterization of PMCA-acetylated tubulin complex

CARBAJAL A, ZAMPAR GG, CHESTA ME, BISIG C.G AND ARCE, C.A

Congreso; XXVI Congreso anual de la Sociedad Argentina de Investigación en Neurociencias; 2011

Plasma Membrane Calcium ATPase (PMCA) is an integral membrane protein that pumps calcium ions from the cytoplasm to the extracellular space. We previously showed that this enzyme interacts with acetylated tubulin, resulting inhibited. Now, we determined that: 1) PMCA from a detergent solubilized membrane preparation coelutes with acetylated tubulin on molecular exclusion chromatography with a MW= 450 KDa (approx.). The discrete MW of the PMCA/tubulin complex suggests that proteins are not part of a membrane fragment but it is formed by a reduced number of tubulin and PMCA (or other) molecules. 2) In vitro, PMCA interacts preferentially with microtubules containing acetylated tubulin. This finding is compatible with a scenario within the cell where PMCA acts as an anchorage site of microtubules with plasma membrane. 3) By testing separately each cytoplasmic fragment of PMCA, we suggest that the cytoplasmic domains CD2 and CD3 are the sites through which PMCA interacts with acetylated tubulin.