ATAT1 (alpha tubulin acetyltransferase 1) is the primary enzyme catalyzing acetylation of lysine 40 on alpha-tubulin, a post-translational modification associated with long-lived stable microtubules 1. This modification is achieved through a unique mechanism where ATAT1 enters microtubules and diffuses through their lumen, preferentially acting on long/old microtubules due to its slow enzymatic rate 1. Beyond its canonical acetyltransferase function, ATAT1 serves non-enzymatic roles, including facilitating axonal transport by promoting molecular motor recruitment and processivity through vesicular acetyl-CoA delivery 2. ATAT1 regulates diverse cellular processes including cell motility, mitosis, and cytoskeletal organization 1, and coordinates B cell immune responses by translocating to the cytoplasm during mechanotransduction to enable actin dynamics and lysosome positioning at immune synapses 3. Emerging disease relevance includes roles in DNA repair through cytoplasmic microtubule acetylation supporting DNA damage response mechanisms 4, and in viral replication where ATAT1 lactylates NAT10 to enhance herpesvirus reactivation 5. ATAT1 loss impairs photoreceptor cilium architecture indirectly through glutamylation dysregulation 6, highlighting its complex integration within cellular signaling networks.