Tubulin must be acetylated at LYS40 of the a- chain to inhibit the Na+, K+-ATPase activity

SANTANDR, V.S., BISIG, C.G., PURRO, S.A., CASALE, C.H., ARCE, C.A AND BARRA, H.S

Pinamar, Argentina

Congreso; Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular (SAIB).; 2005

A subpopulation of membrane tubulin is associated with Na+K+-ATPase in neural and non-neural cell. This association both confers hydrophobic properties to tubulin and inhibit the Na+K+-ATPase activity. Treatment of cells with 1mM L-glutamate provokes dissociation of the complex, leading to increment of active enzyme. The acetylated form of tubulin is present in the tubulin fraction associated with Na+,K+-ATPase, however we do not know whether this type of tubulin is indispensable for interaction with the enzyme. To investigate this question, we used 6-11 B1 antibody specific to acetyl group bound to Lys at position 40 of the a-chain of tubulin, and CAD cells, which lacks acetylated tubulin. In these cells, L-glutamate was unable to stimulate the Na+,K+-ATPase. Using immunoprecipitation procedures, we showed that the Na+,K+- ATPase/tubulin complex was absent in CAD cells. Treatment of cells with deacetylases inhibitors (TSA and tubacin), led to appearance of a significant amount of acetylated tubulin. Under these conditions, the Na+,K+-ATPasel/tubulin complex was found in membranes, and Na+,K+-ATPase activity was inhibited. In addition, L-glutamate was now able to dissociate the complex and to increase enzyme activity. These results indicates that tubulin must be acetylated at Lys 40 to interact with the plasmamembrane Na*,K'-ATPase.