title: Sequences and repertoire of human T cell receptor alpha chain variable region genes in mature T lymphocytes.
abstract: 24 human T cell receptor alpha chain messages have been examined by cDNA sequence analysis and Southern blot. The data indicate that there are approximately 40 alpha chain T cell receptor variable gene segments, which can be divided into 12 families. Comparison of the J gene segments from the cDNAs to previously determined germline J alpha sequences places the number of J alpha gene segments over 21, and indicates their number to be approximately 55. Identical nucleotide sequences in independent isolates of V alpha and J alpha gene segments indicate that hypermutation may not be a common mechanism for the expansion of diversity in these genes, and suggest that the major source of diversity within the alpha chain repertoire is a result of recombinational joinings between germline V alpha and J alpha sequences, combined with imprecise junctional joining. Analysis of the V regions of these alpha chain messages reveals the presence of three domains of hypervariability roughly analogous to the CDR1, CDR2, and CDR3 regions of immunoglobulin.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003101:Collodion; D004247:DNA / Q000302:isolation & purification; D004587:Electrophoresis, Agar Gel; D005796:Genes; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007137:Immunoglobulin alpha-Chains / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*
chemical_list: D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D007137:Immunoglobulin alpha-Chains; D011948:Receptors, Antigen, T-Cell; D003101:Collodion; D004247:DNA