Phosphoribosylformylglycinamidine synthase is a single, long polypeptide in most Proteobacteria and eukarotes. Three proteins are required in Bacillus subtilis and many other species. This is the longest of the three and is designated PurL, phosphoribosylformylglycinamidine synthase II, or FGAM synthase II. [Purines, pyrimidines, nucleosides, and nucleotides, Purine ribonucleotide biosynthesis]
Jiyao W et al.(2023). "The conserved domain database in 2023.",