Phosphoribosylformylglycinamidine synthase involved in the purines biosynthetic pathway. Catalyzes the ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR) and glutamine to yield formylglycinamidine ribonucleotide (FGAM) and glutamate. . This is the function of Ensembl gene identifier ENSG00000178921 (PFAS, phosphoribosylformylglycinamidine synthase).