Regulator of microtubule dynamics that plays a key role in myelination by promoting elongation of the myelin sheath. Acts as a microtubule nucleation factor in oligodendrocytes: specifically localizes to the postsynaptic Golgi apparatus region, also named Golgi outpost, and promotes microtubule nucleation, an important step for elongation of the myelin sheath. Required for both uniform polarized growth of distal microtubules as well as directing the branching of proximal processes. Shows magnesium-dependent GTPase activity;the role of the GTPase activity is unclear. In addition to microtubule nucleation activity, also involved in microtubule bundling and stabilization of existing microtubules, thereby maintaining the integrity of the microtubule network. Regulates microtubule dynamics by promoting tubulin acetylation: acts by inhibiting the tubulin deacetylase activity of HDAC6. Also regulates cell migration: phosphorylation by ROCK1 inhibits interaction with HDAC6, resulting in decreased acetylation of tubul