Light-regulated sampling of protein tyrosine kinase activity.

Protein tyrosine kinases serve as key mediators of signaling pathways, biochemical highways that control various aspects of cell behavior. Although fluorescent reporters of tyrosine kinases have been described, these species can suffer immediate phosphorylation upon exposure to the cellular milieu, thereby hindering a detailed analysis of kinase activity as a function of the cell cycle or exposure to environmental stimuli. The first example of a light-regulated tyrosine kinase reporter is described herein, which allows the investigator to control when kinase activity is sampled. In addition, the set of sensors created in this study contain different fluorophores, each with its own unique photophysical properties, thereby furnishing an array of choices that can be used in combination with other intracellular probes.