ID:ICOS_HUMAN DESCRIPTION: RecName: Full=Inducible T-cell costimulator; AltName: Full=Activation-inducible lymphocyte immunomediatory molecule; AltName: CD_antigen=CD278; Flags: Precursor; FUNCTION: Enhances all basic T-cell responses to a foreign antigen, namely proliferation, secretion of lymphokines, up- regulation of molecules that mediate cell-cell interaction, and effective help for antibody secretion by B-cells. Essential both for efficient interaction between T and B-cells and for normal antibody responses to T-cell dependent antigens. Does not up- regulate the production of interleukin-2, but superinduces the synthesis of interleukin-10. Prevents the apoptosis of pre- activated T-cells. Plays a critical role in CD40-mediated class switching of immunoglobin isotypes (By similarity). SUBUNIT: Homodimer; disulfide-linked. SUBCELLULAR LOCATION: Isoform 1: Cell membrane; Single-pass type I membrane protein (Potential). SUBCELLULAR LOCATION: Isoform 2: Secreted (Potential). TISSUE SPECIFICITY: Activated T-cells. Highly expressed on tonsillar T-cells, which are closely associated with B-cells in the apical light zone of germinal centers, the site of terminal B- cell maturation. Expressed at lower levels in thymus, lung, lymph node and peripheral blood leukocytes. Expressed in the medulla of fetal and newborn thymus. INDUCTION: By phorbol myristate acetate (PMA) and ionomycin. Up- regulated early on T-cells and continues to be expressed into the later phases of T-cell activation. PTM: N-glycosylated. DISEASE: Defects in ICOS are the cause of immunodeficiency common variable type 1 (CVID1) [MIM:607594]. CVID1 is a primary immunodeficiency characterized by antibody deficiency, hypogammaglobulinemia, recurrent bacterial infections and an inability to mount an antibody response to antigen. The defect results from a failure of B-cell differentiation and impaired secretion of immunoglobulins; the numbers of circulating B-cells is usually in the normal range, but can be lo. SIMILARITY: Contains 1 Ig-like V-type (immunoglobulin-like) domain. WEB RESOURCE: Name=ICOSbase; Note=ICOS mutation db; URL="http://bioinf.uta.fi/ICOSbase/"; WEB RESOURCE: Name=GeneReviews; URL="http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/gene/ICOS";
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on Q9Y6W8
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
US Server
Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
