Characterization of arrangement and expression of the T cell receptor γ locus in the sandbar shark

Hao Chen, Sarika Kshirsagar, Ingvill Jensen, Kevin Lau, Roman Covarrubias, Samuel F. Schluter, John J. Marchalonis

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

Ig and T cell receptor (TCR) genes consist of separate genomic elements, which must undergo rearrangement and joining before a functional protein can be expressed. Considerable plasticity in the genomic arrangement of these elements has occurred during the evolution of the immune system. In tetrapods, all Ig and TCR chain elements are arranged as translocons. In teleosts, the Ig heavy and TCR chains are translocons, but light chain genes may occur as clusters. However, in chondrichthyes, all of the Ig light and heavy chain genes are arranged as clusters. These clusters vary in number from <10 to several hundred, depending on isotype and species. Here, we report that the germ-line gene for the TCR γ chain in a chondrichthyan, the sandbar shark (Carcharhinus plumbeus), is present as a single locus arranged in a classic translocon pattern. Thus, the shark utilizes 2 types of genomic arrangements, the unique cluster organization for Ig genes and the "conventional" translocon organization for TCR genes. The TCR γ translocon contains at least 5 V region genes, 3 J segment genes, and 1 C segment. As expected, the third hypervariable segment (CDR3), formed by the rearrangement of the Vγ and Jγ segments, contributed the major variability in the intact V region structure. Our data also suggest that diversity may be generated by mutation in the V regions.

Original languageEnglish (US)
Pages (from-to)8591-8596
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume106
Issue number21
DOIs
StatePublished - May 26 2009
Externally publishedYes

Keywords

  • Diversity
  • Translocon

ASJC Scopus subject areas

  • General

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