Evolutionary redefinition of immunoglobulin light chain isotypes in tetrapods using molecular markers

Sabyasachi Das, Nikolas Nikolaidis, Jan Klein, Masatoshi Nei

Research output: Contribution to journalArticlepeer-review

46 Scopus citations

Abstract

The phylogenetic relationships of Ig light chain (IGL) genes are difficult to resolve, because these genes are short and evolve relatively fast. Here, we classify the IGL sequences from 12 tetrapod species into three distinct groups (κ, λ, and σ isotypes) using conserved amino acid residues, recombination signal sequences, and genomic organization of IGL genes as cladistic markers. From the distribution of the markers we conclude that the earliest extant tetrapods, the amphibians, possess three IGL isotypes: κ, λ, and σ. Of these, two (κ and λ) are also found in reptiles and some mammals. The λ isotype is found in all tetrapods tested to date, whereas the κ isotype seems to have been lost at least in some birds and in the microbat. Conservation of the cladistic molecular markers suggests that they are associated with functional specialization of the three IGL isotypes. The genomic maps of IGL loci reveal multiple gene rearrangements that occurred in the evolution of tetrapod species. These rearrangements have resulted in interspecific variation of the genomic lengths of the IGL loci and the number and order of IGL constituent genes, but the overall organization of the IGL loci has not changed.

Original languageEnglish (US)
Pages (from-to)16647-16652
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number43
DOIs
StatePublished - Oct 28 2008

All Science Journal Classification (ASJC) codes

  • General

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