Just like dual chain AR, except at least one of the fluorophores is a dye. Therefore, this is not fully genetically encoded.
Kraynov, V.S., Chamberlain, C.E., Bokoch, G.M., Schwartz, M. A., Slabaugh, S. and Hahn, K.M. Localized Rac activation dynamics visualized in living cells. Science, 290: 333-337, 2000. Online article | PDF
Hodgson, L., Pertz, O., and Hahn, K.M. Design and Optimization of genetically encoded fluorescent biosensors: GTPase biosensors. Methods Cell Biol, 85:63-81, 2008. [Link downloads PDF] Online article
*Note: this older methods article contains a useful description of biosensor image analysis.
Hodgson, L. Nalbant, P. Shen, F., and Hahn, K. Imaging and photobleach correction of Mero-CBD, sensor of endogenous Cdc42 activation. Methods Enzymol., 406:140-156, 2006. Online article | PDF
*Note: this article is focused on dye-based biosensors, but includes a method to correct for bleaching of any fluorophore.
~ Updated 04/07/2021