Tubulin must be acetylated at lys 40 to inhibit the Na+,K+-atpase activity.

SANTANDER, VERÓNICA S.; BISIG, CARLOS G.; PURRO, SILVIA A.; CASALE, CÉSAR H.; ARCE, CARLOS A.; BARRA, HÉCTOR S.

Pinamar Buenos Aires.

Congreso; PABMB 2005.; 2005

A subpopulation of membrane tubulin is associated with Na+,K+-ATPase in neural and non-neural cells. This association both confers hydrophobic properties to tubulin and inhibits 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 6-11B-1 antibody specific to acetyl group bound to Lys at position 40 of the á-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+-ATPase/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 plasma membrane Na+,K+-ATPase.