Specifically acetylates 'Lys-40' in alpha-tubulin on the lumenal side of microtubules. Promotes microtubule destabilization and accelerates microtubule dynamics; this activity may be independent of acetylation activity. Acetylates alpha-tubulin with a slow enzymatic rate, due to a catalytic site that is not optimized for acetyl transfer. Enters the microtubule through each end and diffuses quickly throughout the lumen of microtubules. Acetylates only long/old microtubules because of its slow acetylation rate since it does not have time to act on dynamically unstable microtubules before the enzyme is released. Required for normal sperm flagellar function. Promotes directional cell locomotion and chemotaxis, through AP2A2-dependent acetylation of alpha-tubulin at clathrin-coated pits that are concentrated at the leading edge of migrating cells. May facilitate primary cilium assembly. acetyl-CoA + L-lysyl-[alpha-tubulin] = CoA + H(+) + N(6)-acetyl-L-lysyl-[alpha-tubulin] Component of the BBSome complex. Interacts with AP2 alpha-adaptins, including AP2A2, but not with AP1 gamma-adaptin (AP1G1/AP1G2); this interaction is required for efficient alpha-tubulin acetylation, hence clathrin-coated pits are sites of microtubule acetylation. Autoacetylation strongly increases tubulin acetylation. Belongs to the acetyltransferase ATAT1 family.