HO1 Recombinant Protein

Heme oxygenase, an essential enzyme in heme catabolism, cleaves heme to form biliverdin, which is subsequently converted to bilirubin by biliverdin reductase, and carbon monoxide, a putative neurotransmitter. Heme oxygenase activity is induced by its substrate heme and by various nonheme substances. Heme oxygenase occurs as 2 isozymes, an inducible heme oxygenase-1 and a constitutive heme oxygenase-2. HMOX1 and HMOX2 belong to the heme oxygenase family. [provided by RefSeq, Jul 2008]

Function: Heme oxygenase cleaves the heme ring at the alpha methene bridge to form biliverdin. Biliverdin is subsequently converted to bilirubin by biliverdin reductase. Under physiological conditions, the activity of heme oxygenase is highest in the spleen, where senescent erythrocytes are sequestrated and destroyed. Exhibits cytoprotective effects since excess of free heme sensitizes cells to undergo apoptosis.

Catalytic activity: Protoheme + 3 AH2 + 3 O2 = biliverdin + Fe2+ + CO + 3 A + 3 H2O.

Subcellular location: Microsome. Endoplasmic reticulum membrane; Peripheral membrane protein; Cytoplasmic side Ref.13.

Tissue specificity: Expressed at higher levels in renal cancer tissue than in normal tissue (at protein level). Ref.10

Induction: Heme oxygenase 1 activity is highly inducible by its substrate heme and by various non-heme substances such as heavy metals, bromobenzene, endotoxin, oxidizing agents and UVA.

Involvement in disease: Heme oxygenase 1 deficiency (HMOX1D) [MIM:614034]: A disease characterized by impaired stress hematopoiesis, resulting in marked erythrocyte fragmentation and intravascular hemolysis, coagulation abnormalities, endothelial damage, and iron deposition in renal and hepatic tissues. Clinical features include persistent hemolytic anemia, asplenia, nephritis, generalized erythematous rash, growth retardation and hepatomegaly.Note: The disease is caused by mutations affecting the gene represented in this entry. Ref.7

Sequence similarities: Belongs to the heme oxygenase family.