The complete nucleotide sequence of mouse immunoglobulin γ2a gene and evolution of heavy chain genes: further evidence for intervening sequence-mediated domain transfer

Open Access
Publisher Website
Google Scholar
Abstract
We have determined the complete nucleotide sequence (1990 base pairs) of mouse immunoglobulin τ2a gene, and compared it with the sequences of other τ subclass genes so far sequenced, i.e. τi and τ2b genes. Divergence of the nucleotide sequences between a compared pair of the τ genes varies extensively among different segments of the gene. For example, comparison of the τ2a and τ2b genes has revealed a remarkable homology in a long continuous segment (about 900 bases) that covers from the 3′ portion of the first intervening sequence to the third intervening sequence. However, there is no particular segment of the τ gene that is conserved universally among the three τ genes. These findings suggest that, during their evolution, segments of the τ genes had been scrambled between different subclass genes through recombinations within intervening sequences, thus providing further evidence for the intervening sequence-mediated domain transfer hypothesis. We have discussed several possible phylogenic trees which can explain the difference of divergence in various segments of the τ genes.