Figure 2.

Optogenetic approaches for perturbation of signaling pathways. (a) Photocaged dimerizer molecules allow for CID to be combined with light-activation. (b) Light-inducible G-protein-coupled receptors (GPCRs) can be engineered by covalently linking the receptor to photoswitchable tethered ligand (PTL). Shown here is the photoswitchable orthogonal remotely tethered ligand (PORTL) design, in which a photochromic ligand is targeted to the GPCR using a SNAP-tag [31]. The ligand is conjugated to an azobenzene moiety, a flexible polyethylene glycol linker, and benzylguanine for conjugation to the SNAP-tag. Optical control of ligand binding is modulated by photoisomerization of the azobenzene moiety, which affects the ability of the ligand to reach the ligand binding pocket. (c) Optogenetic regulation of enzymatic activity can be accomplished using light-sensitive domains that mediate an intramolecular conformational change in the presence of light. (d) Genetically encodable light-sensitive protein dimerization domains allow for reversible and repetitive induction of protein-protein interactions. (e) Exogenous expression of naturally occurring or naturally inspired photosensitive proteins, such as microbial opsins, allow for modulation of signal transduction. DD: dimerization domain, POI: protein of interest, hν: light