title: Intragenic variation of synonymous substitution rates is caused by nonrandom mutations at methylated CpG.
abstract: It has been observed that synonymous substitution rates vary among genes in various organisms, although the cause of the variation is unresolved. At the intragenic level, however, the variation of synonymous substitutions is somewhat controversial. By developing a rigorous statistical test and applying the test to 418 homologous gene pairs between mouse and rat, we found that more than 90% of gene pairs showed a statistical significance in intragenic variation of synonymous substitution rates. Moreover, by examining all conceivable possibilities for the cause of the variation, we successfully found that intragenic variation of synonymous substitutions in mammalian genes is caused mainly by a nonrandom mutation due to the methylation of CpG dinucleotides rather than by functional constraints.
authors.affiliation: Department of Genetics, Graduate University for Advanced Studies, Mishima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tsunoyama
authors.forename: M I
authors.initials: MI
authors.lastname: Bellgard
authors.forename: T
authors.initials: T
authors.lastname: Gojobori
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D018899:CpG Islands; D019175:DNA Methylation; D019143:Evolution, Molecular; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D011506:Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics; D051381:Rats; D016415:Sequence Alignment
chemical_list: D003062:Codon; D011506:Proteins; D012333:RNA, Messenger