4.3.1.B2	metabolism	key metabolic enzyme,which links amino acid and nucleottide biosynthesis. It uses the substrates glutamine and N'-[(5-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide to catalyze the closure of the imidazole ring within histidine biosynthesis and additionally provides 5-aminoimidazole-4-carboxamide ribotide for use in the de novo synthesis of purines	
4.3.1.B2	metabolism	the enzyme catalyzes the fifth step in the histidine biosynthetic pathway located at the branch point to de novo purine biosynthesis	
4.3.1.B2	metabolism	the enzyme links histidine and de novo purine biosynthesis	
4.3.1.B2	physiological function	the enzyme represents a junction between histidine biosynthesis and de novo purine biosynthesis