该基因编码吲哚胺2,3-双加氧酶（ido）-一种血红素酶，催化色氨酸分解为N-甲酰-氨酰肌苷的第一步和限速步骤。这种酶作用于多种色氨酸底物，包括D-色氨酸、L-色氨酸、5-羟基色氨酸、色胺和5-羟色胺。这种酶被认为是在各种病理生理过程中发挥作用，如抗菌和抗肿瘤防御，神经病理学，免疫调节和抗氧化活性。通过在树突状细胞、单核细胞和巨噬细胞中的表达，这种酶通过其必需氨基酸色氨酸的细胞周围分解代谢来调节T细胞的行为。
This gene encodes indoleamine 2,3-dioxygenase (IDO) - a heme enzyme that catalyzes the first and rate-limiting step in tryptophan catabolism to N-formyl-kynurenine. This enzyme acts on multiple tryptophan substrates including D-tryptophan, L-tryptophan, 5-hydroxy-tryptophan, tryptamine, and serotonin. This enzyme is thought to play a role in a variety of pathophysiological processes such as antimicrobial and antitumor defense, neuropathology, immunoregulation, and antioxidant activity. Through its expression in dendritic cells, monocytes, and macrophages this enzyme modulates T-cell behavior by its peri-cellular catabolization of the essential amino acid tryptophan.[provided by RefSeq, Feb 2011]