N-acetyltransferase that mediates the acetylation of the N-terminal residues of alpha- and beta-tubulin (PubMed:33479178). Required for microtubule stability and inhibition of JNK signaling to promote cell survival during development, possibly acting independently of its N-acetyltransferase activity (PubMed:33479178). Necessary for the stabilization of spindle microtubules and for mitosis progression (PubMed:33479178). Regulates microtubule stability by inhibiting Spastin-mediated depolymerization and promoting Eb1-mediated polymerization (PubMed:33479178). acetyl-CoA + N-terminal L-methionyl-[tubulin] = CoA + H(+) + N-terminal N(alpha)-acetyl-L-methionyl-[tubulin] Interacts with microtubules as well as alpha/beta-tubulin heterodimers. In syncytial embryos, localization varies during mitosis (PubMed:33479178). During interphase and prophase, detected around the nucleus including surrounding tubulins (PubMed:33479178). During metaphase and anaphase, highly enriched at the spindle poles and around the spindle microtubules (PubMed:33479178). During telophase, detected in the midbody region containing spindle microtubules (PubMed:33479178). Detected in syncytial embryos and larvae (at protein level). RNAi-mediated knockdown in the posterior compartment of the wing disk, results in adult wings that are reduced in size, display abnormally thin veins and form blisters in the posterior part of the wing (PubMed:33479178). Defects are mainly due to activation of the JNK signaling pathway leading to increased apoptosis in the developing wing (PubMed:33479178). RNAi-mediated knockdown in the dorsoventral (DV) boundary and anterior-posterior (AP) boundary regions of the wing disk, induces notching along the adult wing margin and a reduction in the AP boundary region between the L3 and L4 veins (PubMed:33479178). RNAi-mediated knockdown in the adult thorax causes defects in the abdominal segments (PubMed:33479178). RNAi-mediated knockdown in the adult eyes induces ectopic tissue growth and reduced eye size (PubMed:33479178). RNAi-mediated knockdown in embryos, results in various abnormal mitotic patterns, such as defective chromosome alignments, short spindles and a loss of chromosomes (PubMed:33479178). Belongs to the acetyltransferase family. GNAT subfamily.