IDO2 Gene - Indoleamine 2,3-Dioxygenase 2 | Function, Mutations & Disease

IDO2 encodes indoleamine 2,3-dioxygenase 2, a heme-containing enzyme that catalyzes the first and rate-limiting step in the kynurenine pathway of tryptophan catabolism. It converts L-tryptophan to N-formylkynurenine. IDO2 is expressed in antigen-presenting cells and plays a role in immune regulation, T-cell suppression, and establishing peripheral immune tolerance. It is implicated in cancer immune evasion, autoimmune diseases, and chronic inflammatory conditions.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Kynurenine pathway (tryptophan degradation)

• Tryptophan metabolism (KEGG: hsa00380)

• Immune regulation via tryptophan catabolism

IDO2 is a 420-amino acid heme-dependent dioxygenase that catalyzes the conversion of L-tryptophan to N-formylkynurenine. It shares structural homology with IDO1 but has distinct substrate specificity and lower catalytic efficiency. IDO2 is expressed primarily in antigen-presenting cells and is induced by inflammatory stimuli such as IFN-γ. It contributes to immune tolerance by depleting tryptophan and generating kynurenines that suppress effector T cells and promote regulatory T cell differentiation. Dysregulation of IDO2 is implicated in cancer immune evasion, autoimmune diseases, and chronic inflammation.