Indoleamine 2,3-dioxygenase 2 (IDO2) is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''IDO2''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
IDO2 (indolamine-2,3-dioxygenase) is an enzyme with protein size of 420 amino acids (47 kDa) that is used for
catabolism
Catabolism () is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. Catabolism breaks down large molecules (such as polysaccharides, lipid ...
of
tryptophan
Tryptophan (symbol Trp or W)
is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromat ...
. In organisms, other enzymes participate in
L-tryptophan cleavage, namely
IDO1 and
TDO. Despite IDO1 and IDO2 being closely related enzymes originating by gene duplication and sharing high level (43%) of sequence homology, they differentiate by their kinetics, function and expression pattern. Genes encoding IDO1 and IDO2 have similar genomic structure and are situated closely to each other on chromosome 8. IDO2 is produced in a very limited type of tissues as kidney, liver or antigen presenting cells. IDO2 is less active on substrates of IDO1, better catabolizing other Trp derivates as 5-methoxytryptophan. There are several isoforms in population that comes from alternative splicing. As well as IDO1, IDO2 has been reported in
Treg
The regulatory T cells (Tregs or Treg cells), formerly known as suppressor T cells, are a subpopulation of T cells that modulate the immune system, maintain tolerance to self-antigens, and prevent autoimmune disease. Treg cells are immun ...
differentiation ''in vitro'', suggesting a role in tolerance maintenance. Its expression has been found in several cancers, gastric, colon or renal tumors.
References
Further reading
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