System-wide analyses have underestimated the importance of transcription in animals
Over the last ten years, a number of studies have suggested that, in animal cells, translation and protein turnover play a larger role in determining the different levels at which proteins are expressed than transcription. The major evidence supporting these claims is a weak correlation between system-wide protein and mRNA abundance measurements. A highly cited Nature article by Schwanhausser et al. in 2011 provides the most comprehensive example of such analyses. A new study just published in PeerJ by Li et al., however, questions the conclusions of these papers. This new study suggests that the major reason why protein and mRNA abundance measurements are poorly correlated is because of various types of measurement error in the protein and mRNA abundance, rather than transcription having minimal impact on protein expression levels.