Positive darwinian selection observed at the variable-region genes of immunoglobulins.
To examine Gojobori and Nei's hypothesis that the immunoglobulin heavy-chain variable-region (VH) genes in mammals are subject to diversity-enhancing selection, we studied the rates of synonymous and nonsynonymous nucleotide substitution in the complementarity-determining regions (CDRs) and in the framework regions (FRs) of mouse and human VH genes. The results obtained indicate that the non-synonymous rate is higher than the synonymous rate in CDRs, whereas the reverse is true in FRs. This observation supports Gojobori and Nei's hypothesis and suggests that diversity-enhancing selection (similar to overdominant selection) operates mainly in CDRs and that this is one of the evolutionary factors that increase antibody diversity.
Tanaka
T
T
Center for Demographic and Population Genetics, University of Texas Health Science Center, Houston 77225.
Nei
M
M
D000818:Animals; D001483:Base Sequence; D003062:Codon; D004247:DNA; D014644:Genetic Variation; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D008285:Major Histocompatibility Complex; D051379:Mice; D008969:Molecular Sequence Data; D012641:Selection, Genetic
D003062:Codon; D007135:Immunoglobulin Variable Region; D004247:DNA