UASp sequences regulate expression of a fusion protein composed of the Tag:M(mCd8a) transmembrane domain, the CIBN(ΔNLS)::N-TEV split protease fragment, Tag:AsLOV2(BLITz-Unk) (a TEVp protease target site that is inaccessible in the dark due to being masked by an ASLOV domain) and the intracellular domain of N. Upon illumination with blue light, Tag:AsLOV2(BLITz-Unk) undergoes a conformational change, resulting in the TEVp protease target site becoming accessible. In addition, if the transgene is co-expressed with a source of the CRY2(PHR)::C-TEV split protease fragment, light exposure also allows the CIBN(ΔNLS)::N-TEV and CRY2(PHR)::C-TEV peptides to associate and reconstitute a functional TEVp protease, which can cleave the now accessible TEVp protease target site, releasing the N intracellular domain (which can translocate to the nucleus).