ACETYLATED TUBULIN INHIBITS THE ACTIVITY OF PMCA THAT IS RECOVERED BY ADDITION OF ETHANOL.

MONESTEROLO NE; CAMPETELLI A.; PREVITALI G; CASALE C

Pinamar. Buenos Aires

Congreso; Sociedad Argentina de investigación Bioquímica y Biología Molecular; 2005

SAIB-PABMB

It was previously demonstrated that acetylated tubulin associates with Na+,K+-ATPasa inhibiting its enzymatic activity, and that dissociation of the complex restores its activity. In the present work we demonstrate similar behaviour of plasma membrane Ca+2-ATPasa (PMCA). Studies were carried out by using synaptosomes from rat brain and COS cells in culture. Results indicate that: 1) the higher the amount of tubulin bound to membrane, the lower the enzyme activity; 2) the activation of enzyme by 1% ethanol produces diminution in the amount of tubulin bound to membrane; 3) addition of tubulin to synaptosome preparations inhibits the activity of PMCA that is then recovered by addition of ethanol. These changes of enzyme activity are accompanied with, respectively, higher and lower amount of tubulin bound to membrane; 4) in COS cells, acetylated tubulin/PMCA complex is dissociated as ethanol concentration increases in the culture medium; 5) Treatment with tubulin-Sepharose beads of a detergent-solubilized brain membrane preparation produced precipitation of PMCA. These results show that acetylated tubulin physically interacts with PMCA inhibiting its activity, and that the acetylated tubulin/PMCA complex can be dissociated by ethanol with recovery of PMCA activity.