HO-1
HO-1 (heme oxygenase 1, encoded by HMOX1) is an endoplasmic reticulum membrane enzyme that catalyses the first step of heme breakdown. It is the inducible isozyme of the heme oxygenase family, also known by the alias bK286B10. Browse Assay Genie's current range of HO-1 research reagents below, or read on for the biology behind the target.
HO-1 is an essential enzyme in heme catabolism. It catalyses the oxidative cleavage of heme at the alpha-methene bridge carbon, which is released as carbon monoxide (CO), to generate biliverdin IXalpha. The central heme iron is released as ferrous iron. Biliverdin is subsequently converted to bilirubin by biliverdin reductase, and carbon monoxide has been described as a putative neurotransmitter.
Heme oxygenase activity is induced by its substrate heme and by various nonheme substances. This makes HO-1 the inducible member of a pair of isozymes: the other is the constitutive heme oxygenase-2, encoded by HMOX2. Both HMOX1 and HMOX2 belong to the heme oxygenase family. The HO-1 protein is located at the endoplasmic reticulum membrane. Mouse and rat each have an orthologous Hmox1 gene.
The HMOX1 gene was previously named heme oxygenase (decycling) 1, a name that reflects the ring-opening chemistry of the reaction. Researchers studying heme turnover, iron release or the generation of CO and biliverdin often examine HO-1 expression and activity, and compare it with the constitutive HO-2 isozyme to separate inducible from basal heme oxygenase function.
HO-1 cleaves heme to biliverdin, carbon monoxide and ferrous iron, making it a central enzyme for studying how heme is broken down.
Heme oxygenase activity is induced by heme and by various nonheme substances, so HO-1 is used to study inducible enzyme responses.
Biliverdin from HO-1 is converted to bilirubin by biliverdin reductase, linking the enzyme to downstream bile pigment metabolism.
HO-1 releases carbon monoxide, a putative neurotransmitter, which makes it relevant to research on gaseous signalling molecules.
HO-1 catalyses the oxidative cleavage of heme at the alpha-methene bridge carbon. The products are biliverdin IXalpha, carbon monoxide and ferrous iron. Biliverdin is then converted to bilirubin by biliverdin reductase. This is the first, rate-defining step in heme catabolism.
The HGNC name is heme oxygenase 1, with the previous name heme oxygenase (decycling) 1. Aliases include HO-1 and bK286B10. The HMOX1 gene encodes the protein, and the UniProt entry is P09601. HO-1 should not be confused with HMOX2, which encodes HO-2.
HO-1 is the inducible isozyme, whereas heme oxygenase-2 is constitutive. Both belong to the heme oxygenase family. Mouse and rat have an orthologous Hmox1 gene, so the enzyme can be studied in rodent models; check the datasheet of any product for its validated reactivity.
The constitutive heme oxygenase isozyme and other heme catabolism targets with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P09601; product specifications from Assay Genie datasheets.