cytoFLARE (cytosol-expressed Fast Light- and Activity-Regulated Expression) is a light and calcium gated transcription factor system. This system enables time-gated recording and manipulation of neuronal activity with improved sensitivity and temporal resolution for tagging active neurons.
In this system, a transcriptional factor is tethered in the cytosol using an ERT2 (estrogen ligand-binding domain) via a hLOV and MK2 domain. Upon blue light stimulation, the hLOV1 domain is activated and uncages theaprotease cleavage site that links to the transcription factor. When increased levels in calcium coincide with the blue light, the calmodulin (CaM)-linked protease (TEVp) is recruited to the proximity of the protease cleavage site (TEVcs) via the calcium-dependent interaction between CaM and the CaM-binding peptide (MK2), leading to the cleavage of the TEVcs and thus the release of the TF.
See Zhou et al. 2025 for more details: doi.org/10.1016/j.crmeth.2025.101012
