InterPro domain: IPR020561

Phosphoribosylglycinamide synthetase ( 6.3.4.13 ) (GARS) (phosphoribosylamine glycine ligase) [ 1 ] catalyses the second step in the de novo biosynthesis of purine. The reaction catalysed by phosphoribosylglycinamide synthetase is the ATP-dependent addition of 5-phosphoribosylamine to glycine to form 5'phosphoribosylglycinamide: ATP + 5-phosphoribosylamine + glycine = ADP + P _i + 5'-phosphoribosylglycinamide In bacteria, GARS is a monofunctional enzyme (encoded by the purD gene). Inyeast, GARS is part of a bifunctional enzyme (encoded by the ADE5,7 gene) in conjunction with phosphoribosylformylglycinamidine cyclo-ligase (AIRS) [ 2 ]. In higher eukaryotes, GARS is part of a trifunctional enzyme in conjunction with AIRS and with phosphoribosylglycinamide formyltransferase (GART), forming GARS-AIRS-GART [ 3 ].

This entry represents the A-domain of the enzyme, and is related to the ATP-grasp domain of biotin carboxylase/carbamoyl phosphate synthetase.

1. Nucleotide sequence analysis of genes purH and purD involved in the de novo purine nucleotide biosynthesis of Escherichia coli. J. Biol. Chem. 264, 21239-46
2. The Saccharomyces cerevisiae ADE5,7 protein is homologous to overlapping Drosophila melanogaster Gart polypeptides. J. Mol. Biol. 190, 519-28
3. De novo purine nucleotide biosynthesis: cloning of human and avian cDNAs encoding the trifunctional glycinamide ribonucleotide synthetase-aminoimidazole ribonucleotide synthetase-glycinamide ribonucleotide transformylase by functional complementation in E. coli. Nucleic Acids Res. 18, 6665-72