DUF619 domain of various N-acetylglutamate Kinases and N-acetylglutamate Synthases
DUF619-like: This family includes the DUF619 domain of various N-acetylglutamate synthases (NAGS) of the urea cycle found in humans and fish, the DUF619 domain of the NAGS of the fungal arginine-biosynthetic pathway (FABP), as well as the DUF619 domain present C-terminal of a NAG kinase-like domain in a limited number of predicted NAGSs found in bacteria and Dictyostelium. Ureogenic NAGS is a mitochondrial enzyme catalyzing the formation of NAG from acetylcoenzyme A and L-glutamate. NAGS is an essential allosteric activator of carbamylphosphate synthase I, the first and rate limiting enzyme of the urea cycle. Domain architecture of ureogenic and fungal NAGS consists of an N-terminal NAG kinase-like domain and a C-terminal DUF619 domain. This subgroup also includes the DUF619 domain of the FABP N-acetylglutamate kinase (NAGK), the enzyme that catalyzes the second reaction of arginine biosynthesis; the phosphorylation of the gamma-carboxyl group of NAG to produce N-acetylglutamylphosphate (NAGP) which is subsequently converted to ornithine in two more steps. The nuclear-encoded, mitochondrial polyprotein precursor (ARG5,6) consists of an N-terminal NAGK (ArgB) domain, a central DUF619 domain, and a C-terminal reductase domain (ArgC, N-acetylglutamate phosphate reductase). The DUF619 domain function has yet to be characterized.