Indoleamine 2,3-dioxygenase (IPR000898)

Short name: Indolamine_dOase

Overlapping homologous superfamilies

Family relationships



Indoleamine 2,3-dioxgyenase (IDO, EC: [PMID: 1907934] is a cytosolic haem protein which, together with the hepatic enzyme tryptophan 2,3-dioxygenase, catalyzes the conversion of tryptophan and other indole derivatives to kynurenines. The physiological role of IDO is not fully understood but is of great interest, because IDO is widely distributed in human tissues, can be up-regulated via cytokines such as interferon-gamma, and can thereby modulate the levels of tryptophan, which is vital for cell growth. The degradative action of IDO on tryptophan leads to cell death by starvation of this essential and relatively scarce amino acid. IDO is a haem-containing enzyme of about 400 amino acids. Site-directed mutagenesis showed His346 (P14902) to be essential for haem binding, indicating that this histidine residue may be the proximal ligand. Mutation of Asp274 also compromised the ability of IDO to bind haem, suggesting that Asp274 may coordinate to haem directly as the distal ligand or is essential in maintaining the conformation of the haem pocket [PMID: 12766158].

Other proteins that are evolutionarily related to IDO include yeast hypothetical protein YJR078w; and myoglobin from the red muscle of the archaeogastropodic molluscs, Nordotis madaka (Giant abalone) and Sulculus diversicolor [PMID: 8011076, PMID: 12711393]. These unusual globins lack enzymatic activity but have kept the haem group.

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0020037 heme binding

Cellular Component

No terms assigned in this category.

Contributing signatures

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