Reaction: UROS transforms HMB to URO3
- in pathway: Heme biosynthesis
Cytosolic uroporphyrinogen III synthase (URO3S) catalyzes the conversion of HMB (hydroxymethylbilane) to uroporphyrinogen III, a reaction involving ring closure and intramolecular rearrangement. Uroporphyrinogen III represents a branch point for the pathways leading to formation of heme, chlorophyll and corrins. HMB is rapidly converted from a linear tetrapyrrole to the cyclic form. Deficiencies of URO3S in vivo are associated with congenital erythropoietic porphyria.
Reaction - small molecule participants:
URO3 [cytosol]
H2O [cytosol]
HMBL [cytosol]
Reactome.org reaction link: R-HSA-189488
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Reaction input - small molecules:
preuroporphyrinogen(8-)
Reaction output - small molecules:
uroporphyrinogen III
water
Reactome.org link: R-HSA-189488