Catalyzes the second and fifth step in the 'de novo' purine biosynthesis pathway; contains phosphoribosylamine--glycine ligase (GARS) and phosphoribosylformylglycinamidine cyclo-ligase (AIRS) activities. 5-phospho-beta-D-ribosylamine + ATP + glycine = ADP + H(+) + N(1)-(5-phospho-beta-D-ribosyl)glycinamide + phosphate 2-formamido-N(1)-(5-O-phospho-beta-D-ribosyl)acetamidine + ATP = 5-amino-1-(5-phospho-beta-D-ribosyl)imidazole + ADP + H(+) + phosphate Binds no magnesium or manganese ion per subunit. Purine metabolism; IMP biosynthesis via de novo pathway; 5-amino-1-(5-phospho-D-ribosyl)imidazole from N(2)-formyl-N(1)-(5-phospho-D-ribosyl)glycinamide: step 2/2. Purine metabolism; IMP biosynthesis via de novo pathway; N(1)-(5-phospho-D-ribosyl)glycinamide from 5-phospho-alpha-D-ribose 1-diphosphate: step 2/2. In the N-terminal section; belongs to the GARS family. In the C-terminal section; belongs to the AIR synthase family.