cd00715

Glutamine amidotransferases class-II (GN-AT)_GPAT- type. This domain is found at the N-terminus of glutamine phosphoribosylpyrophosphate (Prpp) amidotransferase (GPATase) . The glutaminase domain catalyzes amide nitrogen transfer from glutamine to the appropriate substrate. In this process, glutamine is hydrolyzed to glutamic acid and ammonia. GPATase catalyzes the first step in purine biosynthesis, an amide transfer from glutamine to PRPP, resulting in phosphoribosylamine, pyrophosphate and glutamate. GPATase crystalizes as a homotetramer, but can also exist as a homdimer.