T cell receptor beta-chain genes in the rat. Availability and pattern of utilization of V gene segments differs from that in the mouse.
We have constructed a specifically primed thymus cDNA library to study the V-region repertoire of the TCR beta-chain in the laboratory rat. From this library, we have isolated and sequenced 14 clones that hybridize with beta-chain constant region probes, eight of which contain V gene segments. Two of these eight contain a V gene segment whose sequence is 85% identical to mouse V beta 14, which has been estimated to be present in mouse thymocyte cDNA at a frequency of only 1.2%. Of the remaining six, four appear to be homologues of known mouse V beta sequences, and average 88% identity with their mouse counterparts. Two additional rat V regions have no homologue yet identified in the mouse, showing only 64 and 73% identity with the most closely related mouse sequences; at least one of these is present and polymorphic in the mouse genome, and may be located near one end of the V beta deletion known in the SWR strain. The availability and pattern of V beta gene segment expression in rat thymus appears, therefore, to differ significantly from the mouse. Two cDNA clones represent germline transcripts which show a J/C splice (one of which is defective) but no D/J rearrangement; two different J segments are used, indicating the presence of promoter activity 5' to these two J segments. In addition, by using V beta-specific probes derived from our cDNA clones, we have analyzed the distribution of V beta alleles among 10 inbred strains of rat. We find that rat V beta gene segments occur predominantly in single member subfamilies, and present evidence for the existence of three TCR V beta haplotypes defined by RFLP.
Williams
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CB
Department of Microbiology and Molecular Genetics, California College of Medicine, Irvine 92717.
Gutman
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GA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D005803:Genes, Immunoglobulin; D005854:Germ Cells / Q000276:immunology; D006239:Haplotypes; D007135:Immunoglobulin Variable Region / Q000235:genetics* / Q000302:isolation & purification; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D012326:RNA Splicing; D051381:Rats; D011913:Rats, Inbred BB; D011914:Rats, Inbred BN; D011915:Rats, Inbred BUF; D011917:Rats, Inbred Lew; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000302:isolation & purification; D012689:Sequence Homology, Nucleic Acid
D007135:Immunoglobulin Variable Region; D011948:Receptors, Antigen, T-Cell