title: Two distinct T-cell receptor alpha-chain transcripts in a rabbit T-cell line: implications for allelic exclusion in T cells.
abstract: Information relevant to allelic exclusion in T cells has been obtained by a study of cDNA clones corresponding to alpha-chain genes of the T-cell receptor in the rabbit T-cell line RL-5. One clone contains a variable-joining-constant (VJC) sequence encoding a complete alpha chain of the T-cell receptor. A second has an identical constant region and includes a distinct variable-joining (VJ) sequence. However, a single-base deletion in the variable region places the remainder of the second transcript out-of-phase and appears to be the product of a rearrangement involving a variable region of the T-cell receptor alpha-chain pseudogene. Presence of two variable-joining-constant (VJC) transcripts in the same cell line indicates that alpha-chain gene rearrangement is not affected by transcription of a complete alpha-chain mRNA and suggests that steps after mRNA synthesis are involved in the allelic exclusion process for alpha-chain genes. Comparison of rabbit alpha-chain sequences with those of man and mouse revealed interspecies conservation in constant and variable regions. Genomic Southern blot analyses using a rabbit constant region of the T-cell receptor alpha-chain probe revealed the presence of a single constant region gene. Hybridization with variable region probes defined two distinct multigenic subfamilies. Homology between certain rabbit and murine variable regions of the T-cell receptor alpha-chain sequences suggests that the existence of subfamilies predated divergence of these species.
mesh_terms: D000483:Alleles; D000818:Animals; D005075:Biological Evolution; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D051379:Mice; D010442:Peptide Chain Initiation, Translational; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D013601:T-Lymphocytes / Q000502:physiology*; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D004247:DNA