Nonsynonymous substitution

A nonsynonymous substitution is a nucleotide mutation that alters the amino acid sequence of a protein. Nonsynonymous substitutions differ from synonymous substitutions, which do not alter amino acid sequences and are (sometimes) silent mutations. As nonsynonymous substitutions result in a biological change in the organism, they are subject to natural selection.

Nonsynonymous substitutions at a certain locus can be compared to the synonymous substitutions at the same locus to obtain the Ka/Ks ratio. This ratio is used to measure the evolutionary rate of gene sequences.[1] If a gene has lower levels of nonsynonymous than synonymous nucleotide substitution, then it can be inferred to be functional because a Ka/Ks ratio < 1 is a hallmark of sequences that are being constrained to code for proteins.

[2] Nonsynonymous substitutions are also referred to as replacement mutations.

  1. ^ Ting Hu and Wolfgang Banzhaf. "Nonsynonymous to Synonymous Substitution Ratio ka/ks: Measurement for Rate of Evolution in Evolutionary Computation" (PDF). {{cite journal}}: Cite journal requires |journal= (help)
  2. ^ Herron, Jon C. (2014). Evolutionary analysis. Freeman, Scott, 1955-, Hodin, Jason A., 1969-, Miner, Brooks Erin,, Sidor, Christian A. (Fifth ed.). Boston. ISBN 978-0321616678. OCLC 859267755.{{cite book}}: CS1 maint: location missing publisher (link)