A photoactivatable Rac1 (PA-Rac1) produced by fusing Rac1 to the LOV domain. In the dark, when the Jα is intact, LOV sterically binds the Rac1 active site. Upon irradiation, the Jα heliz unwinds, prducing a larger linker between Rac and LOV.
The light-induced conformational change of the LOV domain is rapid (< 0.5 milliseconds). The half time for return to the dark state can be adjusted using point mutations (in our hands from 1.7 to 496 seconds, Curr. Protoc. Cell Biol., 73: 21.10.1-14, 2016). Rapid return times are useful for precise kinetic control. Slower return times enable continuous activation with only a brief pulse of light every few minutes.
Wu, Y, Frey, D., Lungu, O. I., Jaehrig, A., Schlichting, I., Kuhlman, B. and Hahn, K.M. A genetically-encoded photoactivatable Rac reveals spatiotemporal coordination of Rac and Rho during cell motility. Nature, 461: 104-110, 2009. PMC2766670. Online article | Free PMC article
Wu, Y.I., Wang, X., He, L., Montell, D. and Hahn, K.M. Spatiotemporal control of small GTPases with light using the LOV domain. Methods Enzymol., 497: 393-407, 2011. PMC3407667. Online article | Free PMC article
~ Updated 04/08/2021