ICOS
The protein encoded by this gene belongs to the CD28 and CTLA-4 cell-surface receptor family. It forms homodimers and plays an important role in cell-cell signaling, immune responses, and regulation of cell proliferation. [provided by RefSeq, Jul 2008]
Full Name
Inducible T Cell Costimulator
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).
Biological Process
Cell-cell adhesion Source: GO_Central
Immune response Source: UniProtKB
T cell costimulation Source: GO_Central
T cell tolerance induction Source: GO_Central
Cellular Location
Isoform 1: Cell membrane
Isoform 2: Secreted
Involvement in disease
Immunodeficiency, common variable, 1 (CVID1):
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 low.
Topology
Extracellular: 21-140
Helical: 141-161
Cytoplasmic: 162-199
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