英和和英

出典:『Wikipedia』 (2011/05/28 05:25 UTC 版)

英語による解説

引用

Subfunctionalization is a model that explains the process by which duplicated genes remain functional in a genome. Duplicated genes are frequently formed in eukaryotic genomes and are thought to be initially redundant in function. One of the extra copies is usually under relaxed selection and therefore acquires degenerative mutations that render it nonfunctional. To explain the high percentage of duplicated genes in eukaryotic genomes several theories have been proposed, such as subfunctionalization. The DDC(Duplication-degenaration-complementation) subfunctionalization model was proposed by Force et al. and is derived from the fact that many genes have multiple independent subfunctions. According to the model after duplication the two copies of the gene acquire deleterious mutations that affect different subfunctions of the ancestral gene. Since both copies are needed to perform the function of the ancestral locus the duplicated loci remain preserved through subfunctionalization. Compared to the ancestral locus, sub-function mutations have a low impact on individual relative fitness and therefore are neutral or nearly neutral to selection. Under such near neutrality genetic drift plays a major role in the likelihood of subfunctionalized genes becoming fixed in the population.