A protein kinase that includes a donor molecule and an acceptor molecule, methods of making the protein kinase, and methods of using the protein kinase are described. Measurement of the conformation of the kinase can be obtained using intramolecular FRET. The protein kinase can be used to, for example, identify conformational changes involved in kinase regulation, that is, as an allostery sensor; to identify kinase-binding molecules including, for example, kinase inhibitors; to identify cancer therapeutics; or for high-throughput screening.