Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

hydroxymethylbilane synthase

Name from literature

uroporphyrinogen synthase

Pathway from literature

porphyrin synthesis

Pathway from KEGG

Metabolism of Cofactors and Vitamins; Porphyrin and chlorophyll metabolism; map00860


Mouse (10090)

Genome localization

9 A5.2|9 26.0 cM[15288 ],


The enzyme works by stepwise addition of pyrrolylmethyl groups until a hexapyrrole is present at the active centre. The terminal tetrapyrrole is then hydrolysed to yield the product, leaving a cysteine-bound dipyrrole on which assembly continues. In the presence of a second enzyme, EC uroporphyrinogen-III synthase, which is often called cosynthase, the product is cyclized to form uroporphyrinogen-III. If EC is absent, the hydroxymethylbilane cyclizes spontaneously to form uroporphyrinogen I.

Rate-limiting Description

"These observations of an associated response of PBGD and PPIX imply that PBGD may be a rate-limiting determinant for the efficacy of delta-ALA-induced photosensitization when used in photodynamic therapy." (9460994)

Gene ontology

Gene ontology

GO:0004418 (F) hydroxymethylbilane synthase activity [P22907 ];
GO:0006783 (P) heme biosynthetic process [P22907 ];




Entrez Gene


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  Last Modified: 2009-03-24  
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