Acetylated tubulin associates with the fifth cytoplasmic domain of Na+/K+-ATPase: possible anchorage site of microtubules to the plasma membrane

We showed previously that NKA (Na+-/K+-ATPase) interacts with acetylated tubulin resulting in inhibition of its catalytic activity. In the present work we determined that membrane-acetylated tubulin, in the presence of detergent, behaves as an entity of discrete molecular mass (320-400 kDa during molecular exclusion chromatography. We also found that microtubules assembled in vitro are able to bind to NKA when incubated with a detergent-solubilized membrane preparation, and that isolated native microtubules have associated NKA. Furthermore, we determined that CD5 (cyloplasmic domain 5 of NKA) is capable of interacting with acetylated tubulin. Taken together. Our results are consistent with the idea that NKA may act as a microtubule-plasma membrane anchorage site through an interaction between acetylated tubulin and CD5.