Conservative Substitutions

 Missense mutations cause the substitution of one amino acid for another in the protein encoded by the mutant gene. The effect of such a change on the protein's function will often depend on how similar the new amino acid is to the original one. Amino acids are classified by their acidity, polarity, hydrophobicity, and structure. Substitutions are considered conservative if the change is between amino acids of the same class. However, a better criterion is whether the substitution has occurred during the evolution of related proteins. The mutations that give rise to conservative amino acid substitutions are considered evolutionarily neutral mutations, or nearly so. Lists of likely conservative substitutions are found in many laboratory manuals, for example (1).

References

1. A. Ellington and J. M. Cherry (1991) In Current Protocols in Molecular Biology (F. M. Ausubel, R. Brent, R. E. Kingston, D. D. Moore, J. G. Seidman, J. A. Smith, and K. Struhl, eds.), Wiley, New York, pp. A.1C.1–A.1C.10.