NAA25 encodes the non-catalytic auxiliary subunit of the NatB complex, which catalyzes N-terminal acetylation of proteins beginning with Met-Asp, Met-Glu, Met-Asn, and Met-Gln residues 1. The NatB complex, composed of catalytic subunit Naa20 and auxiliary subunit Naa25, acetylates approximately 20% of the eukaryotic proteome and is essential for enzymatic activity in plants 2. NAA25 enhances substrate affinity of the catalytic subunit, with the complex showing conserved substrate specificity across eukaryotes 1. N-terminal acetylation by NatB regulates diverse cellular processes including protein targeting, as demonstrated by its role in maintaining Bax in an inactive cytosolic conformation and preventing mitochondrial accumulation 3. The complex is also required for viral protein function, specifically influenza PA-X shutoff activity and viral polymerase activity 4. In plants, NatB depletion reduces growth by 50% and increases sensitivity to osmotic and salt stress, indicating roles in stress responses 2. Genetic variants in NAA25 have been associated with various conditions including type 1 diabetes risk 5, snoring traits 6, and coronary artery disease in Chinese populations 7.