TEVp(S153N)::CaM is an engineered variant of the TEVp protease that has been mutated to carry a S153N amino acid substitution and which is fused to a calmodulin domain. TEVp(S153N)::CaM is designed to be used in the 'cytoFLARE' system, to activate a conditional transcriptional activator that requires both light stimulation and high Ca[2+] to be activated. A 'cytoFLARE' conditional transcriptional activator is a fusion protein containing a sequence that localizes it to the cytosol, a calmodulin-binding peptide, a TEVp protease target site that is caged by a light-sensitive domain in the absence of light stimulation, and a transcriptional activator ('driver') sequence. In the presence of both light stimulation (which uncages the TEVp protease target site in the cytoFLARE conditional transcriptional activator) and high Ca[2+] levels (which brings the TEVp(S153N)::CaM protease into close proximity with the cytoFLARE conditional transcriptional activator due to interaction between the calmodulin and calmodulin-binding peptide domains of the two proteins), the TEVp(S153N)::CaM protease can cleave the TEVp protease target site in the cytoFLARE conditional transcriptional activator, releasing the driver sequence which can then translocate to the nucleus and activate transcription (FBrf0262143).