IDO1: Indoleamine 2,3-Dioxygenase 1
A key immunomodulatory enzyme in tryptophan catabolism and immune tolerance
Gene Information Card
| Symbol | IDO1 |
|---|---|
| Full Name | Indoleamine 2,3-Dioxygenase 1 |
| Gene Type | Protein coding |
| Chromosomal Location | 8p11.21 |
| NCBI Gene ID | 3620 ncbi.nlm.nih.gov/gene/3620 |
| Ensembl ID | ENSG00000131203 |
| UniProt ID | P14902 |
| OMIM ID | 147435 |
| HGNC ID | 5389 |
| Aliases | IDO, INDO, IDO-1 |
Description
IDO1 encodes indoleamine 2,3-dioxygenase 1, 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. IDO1 is expressed in various tissues and cell types, particularly in antigen-presenting cells, and plays a critical role in immune regulation by depleting tryptophan and producing immunomodulatory metabolites. Overexpression is associated with immune tolerance in cancer and chronic infections.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Cancer (various) | IDO1 overexpression depletes tryptophan and generates kynurenines, suppressing T-cell responses and promoting immune evasion. | PMID: 22992522; ClinVar |
| Alzheimer's disease | Increased IDO1 activity leads to neurotoxic kynurenine metabolites and neuroinflammation. | PMID: 25655837 |
| Rheumatoid arthritis | IDO1 upregulation in synovial tissue contributes to local immune suppression and chronic inflammation. | PMID: 16920931 |
| HIV infection | IDO1 activation in dendritic cells induces tryptophan depletion and T-cell dysfunction. | PMID: 15265943 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Placenta | 12.5 | High |
| Lung | 8.2 | Medium |
| Small intestine | 6.7 | Medium |
| Spleen | 5.1 | Medium |
| Liver | 2.3 | Low |
| Brain | 1.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 15.3 | Cervical cancer cell line; high IDO1 expression |
| A549 | 9.8 | Lung adenocarcinoma cell line |
| THP-1 | 7.4 | Monocytic leukemia cell line; inducible by IFN-γ |
| MCF7 | 2.1 | Breast cancer cell line; low basal expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.359C>T (p.Ser120Leu) | Missense | <0.01% | Reduced enzyme activity; reported in ClinVar |
| c.766G>A (p.Gly256Arg) | Missense | <0.01% | Unknown functional effect |
| c.1129G>A (p.Gly377Ser) | Missense | <0.01% | Reported in COSMIC; potential loss of function |
Mutation functional classification
Loss of Function (LOF)
Mutations such as p.Ser120Leu reduce catalytic activity, impairing tryptophan degradation and immune modulation.
Gain of Function (GOF)
No well-characterized gain-of-function mutations reported in IDO1.
Dominant Negative (DN)
No dominant-negative mutations described for IDO1.
View complete mutation data：
Gene Ontology (GO)
| • tryptophan 2 (GO:0004833) | • cytoplasm (GO:0005737) |
| • cytosol (GO:0005829) | • L-tryptophan catabolic process to kynurenine (GO:0019447) |
| • negative regulation of T cell proliferation (GO:0042130) | • T cell homeostasis (GO:0043029) |
Pathways
• KEGG: Tryptophan metabolism (hsa00380)
• KEGG: Kynurenine pathway
• Reactome: Tryptophan catabolism (R-HSA-71240)
• Reactome: IDO1-mediated immune regulation
Protein Summary
IDO1 is a 403-amino-acid heme-containing enzyme that catalyzes the oxidative cleavage of the indole ring of L-tryptophan to form N-formylkynurenine. It is a key regulator of immune responses through tryptophan depletion and production of kynurenine metabolites that suppress T-cell activity and promote regulatory T-cell differentiation. IDO1 is induced by inflammatory stimuli such as interferon-gamma and is a target for cancer immunotherapy.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| IDO1 Knockout HEK293 Cell Line | EDJ-KQ1085 | Human | 3620 | Details Get a Quote |
| IDO1 Knockout HeLa Cell Line | EDJ-KQ53658 | Human | 3620 | Details Get a Quote |
| IDO1 Knockout A-549 Cell Line | EDJ-KQ62132 | Human | 3620 | Details Get a Quote |
| IDO1 Knockout HCT 116 Cell Line | EDJ-KQ70622 | Human | 3620 | Details Get a Quote |
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