Protein kinases have a central role in many cellular functions including transmitting signals received at the cell surface to pathways within the cell, cell-cell communication, cell cycle control, cell morphology and motility, and many other processes. Multiple kinases are often involved in the regulation of specific pathways, so that the role of each kinase is difficult to determine. This is complicated further by the fact that kinases have overlapping substrate specificities. Recently a chemical method has been developed by the PI for directly tracing kinase substrates using an engineered kinase, which accepts an unnatural phosphodonor with a gamma 32P label. This research will explore substrate selectivity in the platelet derived growth factor receptor (PDGFR) kinase pathway in fibroblasts. This pathway is important in controlling entry in to the cell cycle as well as fibroblast motility and morphology. In this project the substrates that are phosphorylated by c-Src after it is recruited to the stimulated PDGFR will be determined. These studies will provide a detailed picture of how 2 kinases act to stimulate complex cell signaling cascades in fibroblasts. The use of chemical tags for individual kinases in these pathways will enable better resolution of how these receptors coordinate with the nonreceptor tyrosine kinases to finely control important cell responses.
