the co-stimulatory signal during t-cell activation
| PAG Title | the co-stimulatory signal during t-cell activation |
| PAG ID | WAG001008 |
| Type | P |
| Source Link |  BioCarta |
| Publication Reference | NA |
| PAG Description | For a T cell to be activated by a specific antigen, the T cell receptor must recognize complexes of MHCI with the antigen on the surface of an antigen-presenting cell. T cells and the T cell receptor complex do not respond to antigen in solution, but even for the specific antigen they only respond to antigen-MHC-1 complexes on the cell surface. This interaction is necessary for T cell activation, but it is not sufficient. T cell activation also requires a co-stimulatory sigl involving interaction of CD28 on the T cell with CD80 or CD86 (B7 family genes) on the antigen-presenting cell. CD28 activates a sigl transduction pathway acting through PI-3K, Lck and Grb-2/ITK to provide its co-stimulatory sigl for T cell activation. Another means to control T cell activation is by expressing factors that down-regulate T cell activation. Sigling by activated T cell receptors induces expression of CTLA-4, a receptor that opposes T cell activation. CTLA-4 has a higher affinity than CD28 for B7 proteins, termiting T cell activation. ICOS is a protein related to CD28 that is only expressed on activated T cells, and that provides another important co-stimulatory sigl. The requirement for co-stimulatory sigls provides additiol control mechanisms that prevent ippropriate and hazardous T cell activation. |
| Species | Homo sapiens |
| Quality Metric Scores | nCoCo Score: 4,494 |
| Information Content | Rich |
| Other IDs | |
| Base PAG ID | WAG001008 |
| Human Phenotyte Annotation | |
| Curator | PAGER curation team |
| Curator Contact | PAGER-contact@googlegroups.com |
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