We show that the predicted protein levels of functionally related proteins change in a coordinated fashion over many unicellular organisms. For each protein, we created a profile containing a protein abundance measure in each of a set of organisms. We show that for functionally related proteins these profiles tend to be correlated. Using the Codon Adaptation Index as a predictor of protein abundance in 48 unicellular organisms, we demonstrated this phenomenon for two types of functional relations: for proteins that physically interact and for proteins involved in consecutive steps within a metabolic pathway. Our results suggest that the protein abundance levels of functionally related proteins co-evolve.
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We thank Norman Grover for useful discussions. We also thank the members of the laboratory, and especially Yael Altuvia, Ruth Hershberg, Esti Yeger-Lotem and Galit Lipsitz for their helpful comments. This study was supported by the Israeli Science Foundation, administered by the Israeli Academy of Sciences and Humanities. Funding to pay the Open Access publication charges for this article was provided by the Israeli Science Foundation.