Type 1 glutamine amidotransferase (GATase1) domain found in imidazole glycerol phosphate synthase (IGPS)
Type 1 glutamine amidotransferase (GATase1) domain found in imidazole glycerol phosphate synthase (IGPS). IGPS incorporates ammonia derived from glutamine into N1-[(5'-phosphoribulosyl)-formimino]-5-aminoimidazole-4-carboxamide ribonucleotide (PRFAR) to form 5'-(5-aminoimidazole-4-carboxamide) ribonucleotide (AICAR) and imidazole glycerol phosphate (IGP). The glutamine amidotransferase domain generates the ammonia nucleophile which is channeled from the glutaminase active site to the PRFAR active site. IGPS belong to the triad family of amidotransferases having a conserved Cys-His-Glu catalytic triad in the glutaminase active site.