The T cell receptor (TcR) β chain is encoded by a 1.3-kb mRNA which contains variable (V), diversity (D), joining (J) and constant (C) regions. A shorter 1.0-kb transcript with C but no V sequences is found in thymocytes, α/β and γ/δ T lymphocytes and natural killer cells.The origin, clonal variability and function of this transcript is unknown. We isolated cDNA clones representative of the 1.0-kb mRNA from cDNA libraries of either polyclonal or clonal natural killer and γ/δ lymphocytes. Ten different types of cDNA clones belonging to three separate groups were identified: (a) "J-C clones" consisting of one of five Jβ regions and the corresponding Cβ1 or Cβ2 regions; (b) "D-J-C clones" composed of Dβ1/ or Dβ2/Jβ rearranged sequences and Cβ1 or Cβ2 sequences; (c) "5′ C clones" made up of Cβ1 or Cβ2 regions preceded by the corresponding genomic 5′ flanking region. The presence of recombination signal sequences in J-C and D-J-C clones suggests that the first derive from mRNA transcribed from promoters located in the 5′ J region and the second from mRNA transcribed from promoters situated in the 5′ D region. Nucleotide sequence analysis demonstrated that only three of the ten types of clones isolated had the potential to code a short cytoplasmic Tβ protein with a variable D-Jβ N terminus. These findings have implications for the mechanisms of Tβ germ-line transcription and the function of the Tβ transcripts.
|Number of pages||6|
|Journal||European Journal of Immunology|
|Publication status||Published - Jun 1991|
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