Moving from transcriptional to phospho-evolution: generalizing regulatory evolution?

Much of biological diversity is thought to arise from changes in regulatory networks. Although the role of transcriptional regulation has been well established, the contribution to evolution of changes at other levels of regulation has yet to be addressed. Using examples from the literature and recent studies on the evolution of protein phosphorylation, we argue that protein regulatory networks also play a prime role in generating diversity within and between species. Because there are several analogies between the regulation of protein functions by kinases and the regulation of gene expression by transcription factors, the principles that guide transcriptional regulatory evolution can also be explored in kinase-substrate networks. These comparisons will allow us to generalize existing models of evolution across the complex layers of the cell's regulatory links.