The rate of protein evolution varies more than 1000-fold
and, for the past 30 years, it was thought that the rate
was determined by protein function. Drummond and
co-workers have now shown that a single factor
underlying mRNA expression, protein abundance and
synonymous codon usage is the chief causal agent of
protein evolutionary rate in yeast. It will be interesting
to see whether this is shown to be a universal rule for all
biological systems
