Bovine NK-lysin: Copy number variation and functional diversification

The cattle genome contains expanded families of several genes involved in innate immunity. A single copy of the NK-lysin gene is annotated in the genomes of most mammals, including humans, but this study identified a family of NK-lysin genes in cattle consisting of four functional members. Although this family mirrors the numerical expansion of other immune-related genes, including interferons, defensins, and cathelicidins, in the cattle genome, we also see a diversification of function exhibited by differential tissue expression in the gene family. The current state of this site in the bovine genome appears to capture the evolutionary transition from copy number variation to the fixation of novel gene function within a segmentally duplicated region.