ICOS

Chr 2q33.2

inducible T cell costimulator

Aliases:: AILIM, CD278
MANE:: ENST00000316386.11

OMIM: 604558 ↗NCBI: 29851 ↗Ensembl ↗

Annotations refreshed 11 hours ago.

Predicted protein structure

AlphaFold predicted structure

ICOS · Q9Y6W8

v62025-08-01

Predicted Aligned Error matrix for ICOS — diagonal shows residue index, colour shows pairwise prediction confidence (lower is better) — Predicted Aligned Error

Mean pLDDT

74.0/ 100

Confident

199 residues

Confidence breakdown

Very high(≥ 90)22%
Confident(70–90)36%
Low(50–70)33%
Very low(< 50)9%

Open interactive 3D viewer

AlphaFold (Jumper et al., 2021) · CC BY 4.0

Clinical relevance (Genomics England PanelApp)

Diagnostic Grade (Green)

COVID-19 research
BIALLELIC, autosomal or pseudoautosomal
Gastrointestinal epithelial barrier disorders
BIALLELIC, autosomal or pseudoautosomal
Infantile enterocolitis & monogenic inflammatory bowel disease
BIALLELIC, autosomal or pseudoautosomal
Intestinal failure or congenital diarrhoea
BIALLELIC, autosomal or pseudoautosomal
Primary immunodeficiency or monogenic inflammatory bowel disease
BIALLELIC, autosomal or pseudoautosomal

Disease associations (Open Targets)

immunodeficiency, common variable, 1
0.73
common variable immunodeficiency
0.68
hypothyroidism
0.48
severe combined immunodeficiency
0.46
combined immunodeficiency
0.46
recurrent infections associated with rare immunoglobulin isotypes deficiency
0.46
basal cell carcinoma
0.41
myxedema
0.40
cancer
0.39
skin neoplasm
0.39

Score is the Open Targets composite evidence score (0-1). Higher = stronger gene-disease association.

Protein function (UniProt)

Inducible T-cell costimulator

Stimulatory receptor expressed in activated or antigen-experienced T-cells that plays an important role in the immune response (PubMed:9930702). Upon binding to its ligand ICOSL expressed on antigen presenting cells (APCs), delivers costimulatory signals that enhances all basic T-cell responses to a foreign antigen, namely proliferation, secretion of lymphokines including IL10, up-regulation of molecules that mediate cell-cell interaction, and effective help for antibody secretion by B-cells (PubMed:33033255). Also acts as a costimulatory receptor critical for the differentiation of T follicular regulatory cells upon immune challenges such as viral infection (PubMed:27135603). Mechanistically, potentiates TCR-induced calcium flux by augmenting PLCG1 activation and actin remodeling (By similarity). In addition, activates PI3K signaling pathways independently of calcium flux (PubMed:30523347). Essential both for efficient interaction between T and B-cells and for normal antibody responses to T-cell dependent antigens. Prevents the apoptosis of pre-activated T-cells. Plays a critical role in CD40-mediated class switching of immunoglobin isotypes (By similarity)