Journal of Molecular Evolution

, Volume 21, Issue 1, pp 58–71

Nonrandomness of point mutation as reflected in nucleotide substitutions in pseudogenes and its evolutionary implications

  • Wen-Hsiung Li
  • Chung-I Wu
  • Chi-Cheng Luo
Article

DOI: 10.1007/BF02100628

Cite this article as:
Li, W., Wu, C. & Luo, C. J Mol Evol (1984) 21: 58. doi:10.1007/BF02100628

Summary

We have obtained a revised estimate of the pattern of point mutation by considering more pseudogene sequences. Compared with our previous estimate, it agrees better with expectations based on the double-strand structure of DNA. The revised pattern, like the previous one, indicates that mutation occurs nonrandomly among the four nucleotides. In particular, the proportion of transitional mutations (59%) is almost twice as high as the value (33%) expected under random mutation. The same high proportion of transitions is observed in synonymous substitutions in genes. The proportion of transitional changes observed among electrophoretic variants of human hemoglobin is about the same as that predicted by the revised pattern of mutation. We also show that nonrandom mutation increases, by about 15%, the proportion of synonymous mutations due to single-nucleotide changes in the codon table, and increases, from 10% to 50%, the rate of synonymous mutation in the seven genes studied. However, nonrandom mutation reduces (by about 10%) the proportion of polar changes among nonsynonymous mutations in a gene. As far as single-nucleotide changes (in the codon table) are concerned, nonrandom mutation only slightly favors relatively conservative amino acid interchanges, and has virtually no effect on the proportions of radical changes and nonsense mutations.

Key words

Mutation patternCodon mutationSynonymous mutationConservative amino acid changeRadical change

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Wen-Hsiung Li
    • 1
  • Chung-I Wu
    • 1
  • Chi-Cheng Luo
    • 1
  1. 1.Center for Demographic and Population GeneticsUniversity of Texas Health Science CenterHoustonUSA