The dynamic TCRδ: TCRδ chains in the amphibian Xenopus tropicalis utilize antibody-like V genes.
The content and organization of the Xenopus tropicalis TCRα/δ locus was determined. This locus is highly conserved among tetrapods, with the genes encoding the TCRδ chains embedded with those encoding TCRα. However, the frog TCRα/δ is unusual in that it contains V genes that appear indistinguishable from those in the IgH locus (VH). These V genes, termed VHδ, make up 70% of the V genes at the TCRδ locus and are expressed exclusively in TCRδ chains. Finding TCRδ chains that use antibody-like V domains in frogs is similar to the situation in shark TCRδ variants and TCRμ in marsupials. These results suggest that such unconventional TCR may be more widespread across vertebrate lineages than originally thought and raise the possibility of previously unrealized subsets of T cells. We also revealed close linkage of TCRα/δ, IgH, and Igλ in Xenopus which, in combination with linkage analyses in other species, is consistent with the previous models for the emergence of these antigen receptor loci.
Parra
Zuly E
ZE
Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, NM 87131-0001, USA.
Ohta
Yuko
Y
Criscitiello
Michael F
MF
Flajnik
Martin F
MF
Miller
Robert D
RD
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D002874:Chromosome Mapping; D004247:DNA / Q000032:analysis*; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D016694:Gene Rearrangement, delta-Chain T-Cell Antigen Receptor; D019676:Genes, T-Cell Receptor delta; D007135:Immunoglobulin Variable Region / Q000235:genetics; D015394:Molecular Structure; D010802:Phylogeny; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism
D000906:Antibodies; D007135:Immunoglobulin Variable Region; D016692:Receptors, Antigen, T-Cell, gamma-delta; D029867:Xenopus Proteins; D004247:DNA