Plays a role in the regulation of ureagenesis by producing the essential cofactor N-acetylglutamate (NAG), thus modulating carbamoylphosphate synthase I (CPS1) activity. acetyl-CoA + L-glutamate = CoA + H(+) + N-acetyl-L-glutamate Increased by L-arginine. Amino-acid biosynthesis; L-arginine biosynthesis; N(2)-acetyl-L-ornithine from L-glutamate: step 1/4. Homodimer (By similarity). Homotetramer (PubMed:23894642). Highly expressed in the liver and small intestine. Weakly expressed in the kidney, spleen and testis. The amino-acid kinase (AAK) domain mediates binding of the allosteric activator L-arginine. Probably processed by mitochondrial processing peptidase (MPP). The long form has not yet been isolated. Belongs to the acetyltransferase family.