Involved in regulation of microtubule dynamics. Regulates the interaction of microtubules tips with the centrosome and cell cortex. Interacts with eb1 at the microtubule tip, centrosome and kinetochore. Interacts with lis1 in the cortical attachment of microtubules. Associated with the microtubule network. Accumulates at the plus end of microtubules. Expressed throughout the cell cycle (at protein level). Mutants exhibit a disappearance of supernumerary centrosomes and multinuclear cells, and increased sensitivity to the microtubule depolymerizing drug nocodazole. Mutants overexpressing mtaA exhibit supernumerary centrosomes and a cytokinesis defect. Mutants underexpressing mtaA display inhibited growth and a reduction in the number and length of astral microtubes. Belongs to the TOG/XMAP215 family.