MSLAVRVIPCLDVDAGRVVKGVHFENLKDAGDPVELAAEYYRQGADEITFLDVTASSSHRNTMIDVVSRTAEQVFIPMTVGGGVRTPEDVDSLLRCGADKVGVNTAAINDPSLISRVADRFGNQVLVLSVDARREKGEQHTQSGFEVTTMGGRKSTGIDAIWWVKRAEQLGAGEILLNSMDADGTKEGFDLEMIRAVRKEVKIPIIASGGAGKVEDFPPAIEAGADAVLAASVFHYGILTIADVKAELKKHGYTVR Imidazole glycerol phosphate synthase subunit HisF IGP synthase subunit HisF HIS6_BIFLS IGP synthase cyclase subunit Blon_1063 hisF ImGP synthase subunit HisF BLIJ_1087 256 IGPS catalyzes the conversion of PRFAR and glutamine to IGP, AICAR and glutamate. The HisF subunit catalyzes the cyclization activity that produces IGP and AICAR from PRFAR using the ammonia provided by the HisH subunit (By similarity).