Evolutionary Framework for Protein Sequence
Evolution and Gene Pleiotrophy
Xun Gu 1*
1 Iowa State University
* To whom correspondence should be addressed. E-mail: xgu{at}iastate.edu.
Submitted on October 5, 2006
Revised on December 19, 2006
Accepted on 8 January 2007
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Abstract |
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In this article, we have developed an evolutionary model for protein sequence evolution. First, gene pleiotrophy is characterized by K distinct but correlated components(molecular phenotypes) that affect the organismal fitness. Second, these K-molecular phenotypes are under stabilizing selection with micro-adaptation due to random optimal shifts, the SM-model. Third, random mutations in the coding region of the gene generate a correlated distribution of K-molecular phenotypes. Under this SM model, we further develop a statistical method to estimate the 'effective' number of molecular phenotypes (Ke) of the gene. Therefore, for the first time we can empirically evaluate gene pleiotrophy from the protein sequence analysis. Case-studies of vertebrate proteins have indicated a typically Ke around 6 - 9. We demonstrate that the newly-developed SM model of protein evolution may provide a basis for exploring genomic evolution and correlations.
Key Words:
gene pleiotrophy, microadaptation, mutation, rate of protein sequence, stabilizing selection
