Conserved Site

Haem oxygenase conserved site (IPR018207)

Short name: Haem_oxygenase_CS


Haem oxygenase (EC: (HO) [PMID: 3290025] is the microsomal enzyme that, in animals, carries out the oxidation of haem, it cleaves the haem ring at the alpha-methene bridge to form biliverdin and carbon monoxide [PMID: 3032976]. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. In mammals there are three isozymes of haem oxygenase: HO-1 to HO-3. The first two isozymes differ in their tissue expression and their inducibility: HO-1 is highly inducible by its substrate haem and by various non-haem substances, while HO-2 is non-inducible. It has been suggested [PMID: 8093563] that HO-2 could be implicated in the production of carbon monoxide in the brain where it is said to act as a neurotransmitter. In the genome of the chloroplast of red algae as well as in cyanobacteria, there is a haem oxygenase (gene pbsA) that is the key enzyme in the synthesis of the chromophoric part of the photosynthetic antennae [PMID: 9326680]. A haem oxygenase is also present in the bacteria Corynebacterium diphtheriae (gene hmuO), where it is involved in the acquisition of iron from the host haem [PMID: 9006041]. There is, in the central section of these enzymes, a well-conserved region centred on a histidine residue.

GO terms

Biological Process

GO:0055114 oxidation-reduction process

Molecular Function

GO:0004392 heme oxygenase (decyclizing) activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
PROSITE patterns