TUBULIN AND Na+/K+-ATPase: ITS ASSOCIATION IN HUMAN ERYTROCYTES MEMBRANES.

MONESTEROLO N; MANCINI, M; VASQUEZ C; CAMPETELLI A; SANTANDER V; PREVITALI G; CASALE C

Rosario. Argentina

Congreso; Sociedad Argentina de investigación Bioquímica y Biología Molecular; 2006

SAIB

Acetylated tubulin is associated with plasma membrane Na+,K+-ATPase inhibiting its enzymatic activity, in neural and non-neural cells. We studied the presence of this association in human erythrocytes membrane (HEM). We determinated in HEM: 1) different tubulin isotypes, 2) hydrophobic properties of membrane tubulin, 3) capacity of the membrane to convert hydrophilic in hydrophobic tubulin, 4) effect of exogen tubulin on Na+,K+-ATPase activity in membranes. Results indicated that HEM contain 4-fold less tubulin that brain plasma membrane and is 50% less acetylated. As others cells, HEM?s tubulin is a peripherical membrane protein, probably by its association with integral membrane protein. HEM were able to associate hydrophilic tubulin of rat brain and convert it in hydrophobic component, inhibiting its Na+,K+-ATPase activity. Double inmunofluorescence observed by confocal microscopy indicated that tubulin and Na+,K+-ATPase co-localize at the periphery of human erythrocytes. Biochemical experiment using isolated human erythrocytes demonstrated that L-glutamate increase the Na+,K+-ATPase activity and decrease of the amount of acetylated tubulin of the HEM. This effect is reverted by glucose addition. These result show that the acetylated tubulin may be involved in the modulation of the control of Na+ and K+ transport in human erythrocytes by its interaction with ATPase.