 GAR + fTHF → fGAR + THF

The fourth is catalyzed by phosphoribosylformylglycinamidine synthase.fGAR + L-Glutamine + ATP → fGAM + L-Glutamate + ADP + Pi

The fifth is catalyzed by AIR synthetase (FGAM cyclase).fGAM + ATP → AIR + ADP + Pi + H2O

The sixth is catalyzed by phosphoribosylaminoimidazole carboxylase.