FIG. 1.

Model pathways for metabolic integration studies. Schematically shown are the pathways for purine mononucleotide, histidine, and thiamine biosynthesis. The gene products involved are indicated in the relevant part of each pathway. Abbreviations: IGP, imidazoleglycerol phosphate; PRFAR, phosphoribulosyl-formimino-5-aminoimidazole carboxamide ribonucleotide; PRPP, 5′-phosphoribosyl-1-pyrophosphate; GTP, GMP; THZ-P, 4-methyl-5(β-hydroxyethyl)thiazole phosphate; HMP-PP, 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate.