title: Unusual organization and diversity of T-cell receptor alpha-chain genes.
abstract: T lymphocytes recognize cell-bound antigens in the molecular context of the self major histocompatibility complex (MHC) gene products through the surface T-cell receptor(s). The minimal component of the T-cell receptor is a heterodimer composed of alpha and beta subunits, each of relative molecular mass (Mr) approximately 45,000 (refs 1-3). Recently, complementary DNA clones encoding these subunits have been isolated and characterized along with that of a third subunit of unknown function, termed gamma (refs 4-9). These studies revealed a primary structure for each subunit that was clearly similar to that of immunoglobulin and indicated a somatic rearrangement of corresponding genes that are also immunoglobulin-like. Recently, the analysis of the sequence organization of the T-cell receptor beta-chain and T-cell-specific gamma-chain gene families has been reported. We now present an initial characterization of the murine T-cell receptor alpha-chain gene family, and conclude that although it is clearly related to the gene families encoding immunoglobulins, T-cell receptor beta-chains and also T-cell gamma-chains, it shows unique characteristics. There is only a single constant (C) region gene segment, which is an exceptionally large distance (approximately 20-40 kilobases (kb) in the cases studied here) from joining (J) gene segments. In addition, the J cluster and the variable (V) segment number seen to be very large. Finally, in the case studied here, a complete alpha-chain gene shows no somatic mutation and can be assembled directly from V alpha, J alpha and C alpha segments without inclusion of diversity (D alpha) segments.
authors.forename: A C
authors.initials: AC
authors.lastname: Hayday
authors.forename: D J
authors.initials: DJ
authors.lastname: Diamond
authors.forename: G
authors.initials: G
authors.lastname: Tanigawa
authors.forename: J S
authors.initials: JS
authors.lastname: Heilig
authors.forename: V
authors.initials: V
authors.lastname: Folsom
authors.forename: H
authors.initials: H
authors.lastname: Saito
authors.forename: S
authors.initials: S
authors.lastname: Tonegawa
mesh_terms: D000818:Animals; D001483:Base Sequence; D002999:Clone Cells; D003001:Cloning, Molecular; D003602:Cytotoxicity, Immunologic; D004247:DNA / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D004622:Embryo, Mammalian; D005796:Genes; D046911:Macromolecular Substances; D008285:Major Histocompatibility Complex; D051379:Mice; D008810:Mice, Inbred C57BL; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D004247:DNA; D004262:DNA Restriction Enzymes