Chu, J. et al. Nat. Biotechnol. http://dx.doi.org/10.1038/nbt.3550 (2016).

Orange fluorescent proteins (OFPs) are valuable tools for multicolor imaging and also perform well in in vivo imaging as a result of their red-shifted emission spectra. Chu et al. developed CyOFP1 for use in diverse biological imaging applications. CyOFP1 has a long Stokes shift, meaning that there is a relatively wide spectral gap between its excitation and emission maxima. This allows CyOFP1 to be excited with cyan light. One benefit of this cyan excitation is that one wavelength can be used to excite both GFP and CyOFP1, enabling experiments such as simultaneous two-photon imaging of green calcium sensors and CyOFP1 in living mouse brains. The team also showed that CyOFP1 can be fused to nanoluciferase to create a bright probe for in vivo bioluminescence imaging.