Abstract
Recent developments in optogenetics have extended optical control of signaling to intracellular proteins, including Rac, a small G protein in the Rho family. A blue light-sensing LOV (light, oxygen, or voltage) domain derived from Avena sativa (oat) phototropin was fused to the N-terminus of a constitutively active mutant of Rac, via an α-helix (Jα) that is conserved among plant phototropins. The fused LOV domain occluded binding of downstream effectors to Rac in the dark. Exposure to blue light caused a conformational change of the LOV domain and unwinding of the Jα helix, relieving steric inhibition. The LOV domain incorporates a flavin as the photon-absorbing cofactor and can be activated by light in a reversible and repeatable fashion. In cultured cells, global illumination with blue light rapidly activated Rac and led to cell spreading and membrane ruffling. Localized and pulsed illumination generated a gradient of Rac activity and induced directional migration. In this chapter, we will describe the techniques in detail and present some examples of applications of using photoactivatable Rac (PA-Rac) in living cells.
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Acknowledgments
This work was supported by NIH grant NS071216 and UCHC start-up funds.
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Yin, T., Wu, Y.I. (2015). Optogenetics: Optical Control of a Photoactivatable Rac in Living Cells. In: Verveer, P. (eds) Advanced Fluorescence Microscopy. Methods in Molecular Biology, vol 1251. Humana Press, New York, NY. https://doi.org/10.1007/978-1-4939-2080-8_15
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DOI: https://doi.org/10.1007/978-1-4939-2080-8_15
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