The synthesis of cytosolic 5-phosphoribosylglycinamide from 5-phosphoribosylamine and glycine, accompanied by the conversion of ATP to ADP and orthophosphate, is catalyzed by the phosphoribosylglycinamide synthetase domain of the trifunctional protein, "phosphoribosylglycinamide formyltransferase, phosphoribosylglycinamide synthetase, phosphoribosylaminoimidazole synthetase" (GART) (Aimi et al. 1990). The active form of the protein is cytosolic (Gooljarsingh et al. 2001; An et al. 2008).