Postdoc, Molecular & Cellular Biology, University of Arizona
"Not all kinases act as a switch: condition specific signaling through Protein Kinase A"
Host: Andrew Capaldi
Models of cellular processes are frequently based on all-or-nothing statements. E.g. a kinase may be active and phosphorylate all of its targets – or not. In this presentation, I showcase results that highlight the need for a more refined perspective. To improve our understanding of Protein kinase A (PKA) signaling in S. cerevisiae, we determined novel PKA-substrates by phospho-proteomics. Interestingly, we found that some of these proteins are also phosphorylated under a condition where PKA was believed to be inactive. We demonstrated that the phosphorylation level in this condition is highly correlated to a measure of in vivo substrate quality we derived. Based on these results, we propose a model in which substrates of the same kinase yield condition-dependent sets of phosphorylated proteins, which are a function of kinase activity and substrate quality. We are now exploring the molecular basis for PKA-substrate quality.