title: Sequences and repertoire of the human T cell receptor alpha and beta chain variable region genes in thymocytes.
abstract: To compare and contrast the human T cell antigen receptor (TcR) alpha and beta chain messages found in human thymocytes to those previously isolated from human peripheral blood T lymphocytes and other nonthymic sources, 13 TcR alpha and 13 TcR beta cDNA were isolated from a human thymocyte library and the nucleotide sequences were determined. The data indicate that, as was found in the peripheral T lymphocytes, the majority of the TcR alpha and TcR beta chain thymocyte cDNA were derived from potentially functional messages. Although the thymocyte-derived TcR cDNA do not contain any unique structural features when compared to TcR cDNA from mature T lymphocytes, 4 new J alpha segments, 17 new V-gene segments (9 V alpha; 8 V beta) and 7 additional V-gene families (4 V alpha and 3 V beta) and sequences had been identified. The exon C beta O, found in many murine thymocyte TcR beta messages, was not found in over 75 human beta chain messages. Based on these new data, a revised estimate of human TcR V alpha, J alpha and V beta repertoires is calculated. The most significant change has been the increase in the estimated number of human TcR V beta-gene segments to a total of about 100 distributed among about 18 families. The V alpha families are now revised upward to 16, with a total number of V alpha segments of 50. The estimate of the J alpha segments in humans remains between 50-100.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005796:Genes; D006801:Humans; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013601:T-Lymphocytes / Q000502:physiology*; D013950:Thymus Gland / Q000502:physiology*
chemical_list: D011948:Receptors, Antigen, T-Cell; D004247:DNA