Modes of actions of optogenetic switches are illustrated on commonly used switches. (A) PHYB heterodimerizes with its interaction partner PIF upon red light illumination, which can be reversed by far-red light [18]. (B) Upon red light exposure, CPH1 forms homodimers that dissociate with far-red light [19]. (C) CRY2 engages its interaction partner CIBN to form heterodimers upon exposure with blue light [20]. (D) Additionally, CRY2 can form homo-oligomers [21]. (E) The Jα helix of AsLOV2 unwinds upon blue light illumination, thereby uncaging a motif of interest (M) [22,23]. (F) In the iLID switch, the adapter protein SsrA is exposed under blue light, enabling the binding of its interaction partner SspB [24]. Abbreviations: AsLOV2, the light-oxygen-voltage domain of phototropin 1 derived from Avena sativa; CIBN, cryptochrome-interacting basic helix-loop-helix 1 (N-terminal amino acids 1-100); CRY2, cryptochrome 2; M, the motif of interest; PHYB, phytochrome B; PIF, phytochrome interacting factor.