The purine ring is built up one or a few atoms at a time on ribose 5-P H HH 5-Phosphoribosyl HC C-H Formyldycinamide OH OH I-pyrophosphate(PRPP) O=C ribonucleotide(FGAR) glutamine NH Glutamate Glutamin ①OCH2O Glutamate NI 5.Phospho-B- ATP D-ribosylamine →ADP+P OH OH Glvcine H C-HFormylglycinamidine ATP HN=C ribonucleotide (FGAM) N ADP+ P R Steps 1, 3, and 5 are analyzed b NH3 ed by one HC Glycinamide ADP+P multifunctional protein O=C ribonucleotide(GAR) Ho in some eukaryotic cells R HC CH 5-Aminoimidazole N° FormvI H4 folate ribonucleotide (AIR) H2N H4 folateThe purine ring is built up one or a few atoms at a time on ribose 5-P Steps 1, 3, and 5 are catalyzed by one multifunctional protein in some eukaryotic cells