REGULATION OF P-TYPE ATPASES ACTIVITIES BY INTERACTION WITH ACETYLATED TUBULIN

MONESTEROLO, NE; CAMPETELLI, AN; SANTANDER, VS; ARCE, CA; CASALE, CH

Mar del Plata

Congreso; SAIB-Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2007

We previously reported that three P-type ATPases (Na+,K+-, H+- and Ca2+-ATPase) are regulated by a common effector: acetylated tubulin. Interaction of tubulin with these three plasma membrane ATPases, while leading to the formation of a relatively stable protein complex, produces inhibition of their catalytic activities. In this communication, we show that: a) In yeast, tubulin/H+-ATPase complex dissociation is dependent on microtubule dynamics; treatment with nocodazole and/or taxol influence stability of the complex and hence ATPase activity; b) in isolated yeast membranes, tubulin is degraded in a pH-dependent manner; c) Calmodulin, which activates plasma membrane Ca2+-ATPase (PMCA), provokes dissociation of the tubulin/Ca2+-ATPase complex and activates enzyme activity in plasma membrane vesicles from synaptosomes; d) PMCA is activated also by ethanol treatment of the membrane vesicles and this occurs also in cultured cells. These results reinforce the idea that ATPases of the P-type are regulated by their interaction with tubulin and that this is modulated by internal factors such as microtubule dynamics, calmodulin and pH, or external factor such as ethanol.