CHAPTER 8: Quantitative Control of Kinase Activity with a Mathematical Model
Published:18 Sep 2018
Special Collection: 2018 ebook collection
G. Kawamura and T. Ozawa, in Optogenetics: Light-driven Actuators and Light-emitting Sensors in Cell Biology, ed. S. Vriz and T. Ozawa, The Royal Society of Chemistry, 2018, pp. 149-168.
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This chapter presents an optogenetic method to control the function of the protein kinase Akt. This system, photoactivatable Akt (PA-Akt), consists of photoreceptor proteins from Arabidopsis thaliana, cryptochrome 2 (Cry2) and cryptochrome-interacting basic helix–loop–helix 1 (Cib1), which form a complex upon illumination with blue light. In the PA-Akt system, a genetically encoded fusion protein of Cry2 with Akt (Cry2–Akt) and Cib1 anchored to the plasma membrane by a myristoyl sequence (myr–Cib1) is used. The Cry2–Akt and myr–Cib1 pair exhibits kinase activation of Cry2–Akt dependent on illumination with blue light. Selective manipulation of the Cry2–Akt function using light is employed as a spatial and temporal effector of the Akt signaling, which allows identification of dynamic regulation of the Akt signaling. Furthermore, computational modeling of the PA-Akt system predicts the Akt activation pattern as a function of light, which is useful as a generator of an Akt activation pattern for decoding temporal codes of the Akt signaling. Taken together, the PA-Akt platform serves as a perturbation method for the analysis of spatial and temporal patterns of Akt kinase activity in living cells, which provides novel insights into dynamic and diverse functions of Akt.