If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
Synonyms: IMP biosynthesis II
|Superclasses:||Biosynthesis → Nucleosides and Nucleotides Biosynthesis → Purine Nucleotide Biosynthesis → Purine Nucleotides De Novo Biosynthesis → Purine Riboucleotides De Novo Biosynthesis → Inosine-5'-phosphate Biosynthesis|
Pathway Summary from MetaCyc:
De novo biosynthesis of purines starts with the synthesis of IMP, which can be converted to all other purines.
In the bacterium Escherichia coli IMP is synthesized from 5-amino-1-(5-phospho-β-D-ribosyl)imidazole in 6 steps (see inosine-5'-phosphate biosynthesis I). In eukaryotes the pathway consists of only 5 steps. The difference is in the first two steps, which are replaced in eukaryotes with a single reaction.
The first 3 steps of this pathway are catalyzed in the yeast Saccharomyces cerevisiae by individual enzymes, while the last two steps are catalyzed by a single multifunctional enzyme|. Saccharomyces cerevisiae possesses two isozymes of the multifunctional enzyme, encoded by the ADE16 and ADE17 genes. While these isozymes are indistinguishable with respect to activity, cellular location and subunit structure, they do differ in expression levels, and Ade17 is the major isozyme, accounting for approximately 90% activity [Tibbetts00, Tibbetts97].
Superpathways: superpathway of purine nucleotides de novo biosynthesis I
Variants: inosine-5'-phosphate biosynthesis I
Pathway Evidence Glyph:
This organism is not in the expected taxonomic range for this pathway.
Tibbetts00: Tibbetts AS, Appling DR (2000). "Characterization of two 5-aminoimidazole-4-carboxamide ribonucleotide transformylase/inosine monophosphate cyclohydrolase isozymes from Saccharomyces cerevisiae." J Biol Chem 2000;275(27);20920-7. PMID: 10877846
Tibbetts97: Tibbetts AS, Appling DR (1997). "Saccharomyces cerevisiae expresses two genes encoding isozymes of 5-aminoimidazole-4-carboxamide ribonucleotide transformylase." Arch Biochem Biophys 1997;340(2);195-200. PMID: 9143321
Jabrin03: Jabrin S, Ravanel S, Gambonnet B, Douce R, Rebeille F (2003). "One-carbon metabolism in plants. Regulation of tetrahydrofolate synthesis during germination and seedling development." Plant Physiol 131(3);1431-9. PMID: 12644692
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