FB2026_03 , released September 17, 2026
CV Term Report
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General Information
Term hydroxymethylbilane synthase activity ID (Ontology) GO:0004418 (Gene Ontology)
Definition Catalysis of the reaction: H2O + 4 porphobilinogen = hydroxymethylbilane + 4 NH4.[ EC:2 ]
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Genes (FBgn)GO_MOLECULAR_FUNCTION
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 hydroxymethylbilane synthase activity (all annotations which use CV term, excluding "NOT" statements)
     enables | hydroxymethylbilane synthase activity
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  transferase activity
   |__transferase activity, transferring alkyl or aryl (other than methyl) groups
       |__hydroxymethylbilane synthase activity  1 rec.
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Is a transferase activity, transferring alkyl or aryl (other than methyl) groups
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Synonyms
  • "(4-(2-carboxyethyl)-3-(carboxymethyl)pyrrol-2-yl)methyltransferase (hydrolyzing) activity" RELATED[ EC:2 ]
    "(4-[2-carboxyethyl]-3-[carboxymethyl]pyrrol-2-yl)methyltransferase (hydrolysing)" RELATED
    "HMB-synthase activity" RELATED[ EC:2 ]
    "porphobilinogen ammonia-lyase (polymerizing)" RELATED[ EC:2 ]
    "porphobilinogen deaminase activity" RELATED[ EC:2 ]
    "porphobilinogen:(4-[2-carboxyethyl]-3-[carboxymethyl]pyrrol-2-yl)methyltransferase (hydrolysing)" RELATED
    "pre-uroporphyrinogen synthase activity" RELATED[ EC:2 ]
    "uroporphyrinogen I synthase activity" NARROW[ EC:2 ]
    "uroporphyrinogen I synthetase activity" NARROW[ EC:2 ]
    "uroporphyrinogen synthase activity" RELATED[ EC:2 ]
    "uroporphyrinogen synthetase activity" RELATED[ EC:2 ]
Secondary IDs
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EC:2.5.1.61
KEGG_REACTION:R00084
MetaCyc:OHMETHYLBILANESYN-RXN
Reactome:R-HSA-189406 "4 PBGs bind to form HMB"
RHEA:13185