DUF619 domain of N-acetylglutamate kinase (NAGK) of the fungal arginine-biosynthetic pathway
DUF619-NAGK-FABP: DUF619 domain of N-acetylglutamate kinase (NAGK) of the fungal arginine-biosynthetic pathway (FABP). 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, NAGPR). The precursor is cleaved into two distinct enzymes (NAGK-DUF619 and NAGPR) in the mitochondria. Native molecular weights of these proteins indicate that the kinase is an octamer whereas the reductase is a dimer. Arg5,6 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. It also binds and regulates the promoters of nuclear and mitochondrial genes, and may possibly regulate precursor mRNA metabolism. The DUF619 domain function has yet to be characterized.