Protein Domain : Cytotoxic T-lymphocyte protein 4/CD28 IPR040216

Type	Family
Description	T cell-dependent immune processes require cell-surface interactions that mediate the initiation, modulation and the ultimate course of the response.The specificity of T cell recognition is determined by the engagement of the T cell receptor (TCR) on T cells with cognate peptide-MHC complexes presented by antigen presenting cells (APCs). Additional signals are required to sustain and enhance T cell activity, the most important of whichis provided by the engagement of CD28 on T cells with its ligands B7-1 (CD80) and B7-2 (CD86). By contrast, the interaction of B7 isoformswith cytotoxic T lymphocyte-associated molecule-4 CTLA-4, a CD28 homologue receptor on T cells (31% identity), provides inhibitory signals requiredfor down-regulation of the response, while it may also prevent T cell activation by weak TCR signals[ , , , , ].Sequence comparison between human CTLA-4 and CD28 proteins suggests they are homologous, with the highest of degree of similarity being in the juxta- membrane and cytoplasmic regions. In addition, the cytoplasmic domainsof human and murine CTLA-4 are identical, suggesting that this region has important functional properties [].
Short Name	CTLA4/CD28