Nucleoside diphosphate kinase does not directly interact with tubulin nor microtubules

Nucleoside diphosphate kinase has been shown to play a role in proliferation and development. Microtubules have been evoked as a possible target of NDP kinase action; in particular it was proposed that NDP kinase could regulate the cellular pool of polymerizable GTP-tubulin by direct phosphorylation of tubulin bound GDP. We show that this reaction does not occur in vitro and also that NDP kinase does not bind to microtubules both in the presence and absence of MAPs. Thus, any possible physiological effect of NDP kinase on microtubule dynamics is exerted only by modulating the concentrations of free guanine nucleotides in the vicinity of microtubules.