Gn_AT_II_novel. This asparagine synthase-related domain is present in eukaryotes but its function has not yet been determined. The glutaminase domain catalyzes an amide nitrogen transfer from glutamine to the appropriate substrate. In this process, glutamine is hydrolyzed to glutamic acid and ammonia. This domain is related to members of the Ntn (N-terminal nucleophile) hydrolase superfamily and is found at the N-terminus of enzymes such as glucosamine-fructose 6-phosphate synthase (GLMS or GFAT), glutamine phosphoribosylpyrophosphate (Prpp) amidotransferase (GPATase), asparagine synthetase B (AsnB), beta lactam synthetase (beta-LS) and glutamate synthase (GltS). GLMS catalyzes the formation of glucosamine 6-phosphate from fructose 6-phosphate and glutamine in amino sugar synthesis. GPATase catalyzes the first step in purine biosynthesis, an amide transfer from glutamine to PRPP, resulting in phosphoribosylamine, pyrophosphate and glutamate. Asparagine synthetase B synthesizes asparagine from aspartate and glutamine. Beta-LS catalyzes the formation of the beta-lactam ring in the beta-lactamase inhibitor clavulanic acid. GltS synthesizes L-glutamate from 2-oxoglutarate and L-glutamine. These enzymes are generally dimers, but GPATase also exists as a homotetramer.
Jiyao W et al.(2023). "The conserved domain database in 2023.",