The ATP-hydrolysing enzymes (Na(+),K(+))-, H(+)- and Ca(2+)-ATPase are integral membrane proteins that play important roles in the exchange of ions and nutrients between the exterior and interior of cells, and are involved in signal transduction pathways. Activity of these ATPases is regulated by several specific effectors. Here, we review the regulation of these P-type ATPases by a common effector, acetylated tubulin, which interacts with them and inhibits their enzyme activity. The presence of an acetyl group on Lys40 of alpha-tubulin is a requirement for the interaction. Stimulation of enzyme activity by different effectors involves the dissociation of tubulin/ATPase complexes. In cultured cells, acetylated tubulin associated with ATPase appears to be a constituent of microtubules. Stabilization of microtubules by taxol blocks association/dissociation of the complex. Membrane ATPases may function as anchorage sites for microtubules.