title: T-cell antigen receptor genes and T-cell recognition.
abstract: The four distinct T-cell antigen receptor polypeptides (alpha, beta, gamma, delta) form two different heterodimers (alpha:beta and gamma:delta) that are very similar to immunoglobulins in primary sequence, gene organization and modes of rearrangement. Whereas antibodies have both soluble and membrane forms that can bind to antigens alone, T-cell receptors exist only on cell surfaces and recognize antigen fragments only when they are embedded in major histocompatibility complex (MHC) molecules. Patterns of diversity in T-cell receptor genes together with structural features of immunoglobulin and MHC molecules suggest a model for how this recognition might occur. This view of T-cell recognition has implications for how the receptors might be selected in the thymus and how they (and immunoglobulins) may have arisen during evolution.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003198:Computer Simulation; D004247:DNA / Q000032:analysis; D014644:Genetic Variation; D007135:Immunoglobulin Variable Region / Q000276:immunology; D007136:Immunoglobulins / Q000276:immunology; D008285:Major Histocompatibility Complex; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D007135:Immunoglobulin Variable Region; D007136:Immunoglobulins; D011948:Receptors, Antigen, T-Cell; D004247:DNA