Genomic organization of the genes encoding mouse T-cell receptor alpha-chain.
The vertebrate immune system uses two kinds of antigen-specific receptors, the immunoglobulin molecules of B cells and the antigen receptors of T cells. T-cell receptors are formed by a combination of two different polypeptide chains, alpha and beta (refs 1-3). Three related gene families are expressed in T cells, those encoding the T-cell receptor, alpha and beta, and a third, gamma (refs 4-6), whose function is unknown. Each of these polypeptide chains can be divided into variable (V) and constant (C) regions. The V beta regions are encoded by V beta, diversity (D beta) and joining (J beta) gene segments that rearrange in the differentiating T cell to generate V beta genes. The V gamma regions are encoded by V gamma, J gamma and, possibly, D gamma gene segments. Studies of alpha complementary DNA clones suggest that alpha-polypeptides have V alpha and C alpha regions and are encoded by V alpha and J alpha gene segments and a C alpha gene. Elsewhere in this issue we demonstrate that 18 of 19 J alpha sequences examined are distinct, indicating that the J alpha gene segment repertoire is much larger than those of the immunoglobulin (4-5) or beta (14) gene families. Here we report the germline structures of one V alpha and six J alpha mouse gene segments and demonstrate that the structures of the V alpha and J alpha gene segments and the alpha-recognition sequences for DNA rearrangement are similar to those of their immunoglobulin and beta-chain counterparts. We also show that the J alpha gene-segment organization is strikingly different from that of the other immunoglobulin and rearranging T-cell gene families. Eighteen J alpha gene segments map over 60 kilobases (kb) of DNA 5' to the C alpha gene.
Winoto
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Mjolsness
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Hood
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes; D005796:Genes; D007144:Immunoglobulin J-Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics; D046911:Macromolecular Substances; D051379:Mice; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*
D007144:Immunoglobulin J-Chains; D007135:Immunoglobulin Variable Region; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D004247:DNA; D004262:DNA Restriction Enzymes