HAO1
HAO1 (hydroxyacid oxidase 1, also known as GOX or GOX1) is a peroxisomal flavoprotein that oxidises glycolate to glyoxylate. It is a broad-specificity (S)-2-hydroxyacid oxidase and a member of the FMN-dependent alpha-hydroxy acid dehydrogenase family. Browse Assay Genie's current range of HAO1 research reagents below, or read on for the biology behind the target.
HAO1 is a broad-substrate-specificity (S)-2-hydroxyacid oxidase that preferentially oxidises glycolate. The glyoxylate produced can be used by alanine-glyoxylate aminotransferase for the peroxisomal synthesis of glycine. This pathway appears to be an important step in detoxifying glyoxylate, which, if it accumulates, may be metabolised to oxalate with the formation of kidney stones. HAO1 can also oxidise glyoxylate and long-chain hydroxyacids such as 2-hydroxyhexadecanoate and 2-hydroxyoctanoate, but with much lower catalytic efficiency. It is not active on L-lactate or 2-hydroxybutanoate.
In vitro, the enzyme is active with the artificial electron acceptor 2,6-dichlorophenolindophenol (DCIP). Molecular oxygen is believed to be the physiological electron acceptor, which leads to the production of H2O2. The protein sits in the peroxisome matrix and belongs to the FMN-dependent alpha-hydroxy acid dehydrogenase family. HGNC classifies the HAO1 gene within the flavoproteins and the hydroxyacid oxidase family.
According to the NCBI Gene summary, HAO1 is one of three related genes with 2-hydroxyacid oxidase activity. They differ in protein sequence, tissue expression and substrate preference. The HAO1 gene is expressed primarily in liver and pancreas, and its protein is most active on glycolate, a two-carbon substrate, and also acts on 2-hydroxy fatty acids. The transcript seen at high levels in pancreas may represent an alternatively spliced form or the use of multiple near-consensus upstream polyadenylation sites. The previous gene name was hydroxyacid oxidase (glycolate oxidase) 1, and mouse and rat each have a Hao1 ortholog.
HAO1 generates glyoxylate from glycolate, placing it at a point where glyoxylate is either detoxified or may be converted to oxalate.
Accumulated glyoxylate may be metabolised to oxalate with kidney stone formation, which makes HAO1 relevant to studies of this pathway.
HAO1 works in the peroxisome matrix alongside alanine-glyoxylate aminotransferase to support peroxisomal glycine synthesis.
HAO1 is expressed mainly in liver and pancreas, so it is useful for comparing tissue-specific hydroxyacid oxidase activity.
HAO1 is a peroxisomal (S)-2-hydroxyacid oxidase that preferentially oxidises glycolate to glyoxylate. Oxygen is believed to be the physiological electron acceptor, giving H2O2. The glyoxylate can then be used by alanine-glyoxylate aminotransferase to make glycine, which helps detoxify glyoxylate.
HAO1 is the HGNC symbol for hydroxyacid oxidase 1. Aliases are GOX and GOX1, and the earlier gene name was hydroxyacid oxidase (glycolate oxidase) 1. UniProt names the protein 2-hydroxyacid oxidase 1. Its EC number is 1.1.3.15.
HAO1 is one of three related genes with 2-hydroxyacid oxidase activity that differ in sequence, tissue expression and substrate preference. HAO1 is expressed mainly in liver and pancreas and is most active on glycolate. Mouse and rat both have a Hao1 ortholog.
Other hydroxyacid oxidases, peroxisomal enzymes and glyoxylate-metabolism targets may be listed as pages become available.
Gene and protein annotations from HGNC, NCBI Gene and UniProt Q9UJM8; product specifications from Assay Genie datasheets.