Conserved organization of the human and murine T-cell receptor beta-gene families.
Generation of an immune response depends on the interaction of haematopoietic cell types, among which T cells and their receptors are of central importance. The T-cell receptor is a heterodimer consisting of disulphide-linked alpha and beta-chains, each chain divided into variable (V) and constant (C) regions. The beta-chain is encoded by the rearrangement of separate variable (V beta), diversity (D beta) and joining (J beta) gene segments during T-cell differentiation. To examine the mechanisms of somatic DNA rearrangement and evolution of the beta-gene segments, we have constructed a physical map of the human T-cell receptor beta-chain family containing 40 V beta gene segments as well as both C beta gene clusters. A comparison of the published nucleotide sequences of human and murine V beta gene segments reveals 12 examples of gene segments sharing 65% or more interspecies homology. The relative order of these human and murine V beta gene segment homologues is also conserved along the chromosome, apart from more extensive human gene duplication, presumably as a consequence of constraints imposed on evolutionary mechanisms operating to diversify these gene families or of selective pressures operating to maintain order.
Lai
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E
Division of Biology, California Institute of Technology, Pasadena 91125.
Concannon
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P
Hood
L
L
D000818:Animals; D005075:Biological Evolution; D002874:Chromosome Mapping; D004262:DNA Restriction Enzymes; D004587:Electrophoresis, Agar Gel; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D009693:Nucleic Acid Hybridization; D011948:Receptors, Antigen, T-Cell / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D004262:DNA Restriction Enzymes