Journal of Molecular Evolution

, Volume 25, Issue 1, pp 58–64

Ubiquitin genes as a paradigm of concerted evolution of tandem repeats

  • Paul M. Sharp
  • Wen-Hsiung Li

DOI: 10.1007/BF02100041

Cite this article as:
Sharp, P.M. & Li, WH. J Mol Evol (1987) 25: 58. doi:10.1007/BF02100041


Ubiquitin is remarkable for its ubiquitous distribution and its extreme protein sequence conservation. Ubiquitin genes comprise direct repeats of the ubiquitin coding unit with no spacers. The nucleotide sequences of several ubiquitin repeats from each of humans, chicken,Xenopus, Drosophila, barley, and yeast have recently been determined. By analysis of these data we show that ubiquitin is evolving more slowly than any other known protein, and that this (together with its gene organization) contributes to an ideal situation for the occurrence of concerted evolution of tandem repeats. By contrast, there is little evidence of between-cluster concerted evolution. We deduce that in ubiquitin genes, concerted evolution involves both unequal crossover and gene conversion, and that the average time since two repeated units within the polyubiquitin locus most recently shared a common ancestor is approximately 38 million years (Myr) in mammals, but perhaps only 11 Myr inDrosophila. The extreme conservatism of ubiquitin evolution also allows the inference that certain synonymous serine codons differing at the first two positions were probably mutated at single steps.

Key words

Molecular evolution Protein sequence conservation Synonymous substitution Unequal crossover Gene conversion 

Copyright information

© Springer-Verlag New York Inc. 1987

Authors and Affiliations

  • Paul M. Sharp
    • 1
    • 2
  • Wen-Hsiung Li
    • 1
  1. 1.Center for Demographic and Population GeneticsUniversity of TexasHoustonUSA
  2. 2.Department of GeneticsTrinity CollegeDublin 2Ireland

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