Figure 5.

Optogenetic control of T cell signaling. (A) In the opto-ligand-TCR system, PIF is inserted into the extracellular domain of TCRβ and tetramerized PHYB serves as ligand. Continuous red light exposure leads to the constant switching between the PIF-binding and non-binding states of PHYB. Higher light intensities induce higher switching rates, enabling the control of the binding half-life by the light intensity applied [87]. (B) The LOVTRAP-based Zdk CAR comprises Zdk fused to CAR and AsLOV2, presented on a supported lipid bilayer, as ligand. CAR-Zdk interacts with AsLOV2 stimulating ζ-chain-dependent signaling in the dark. Upon blue light exposure, AsLOV2 and Zdk dissociate correlating with the termination of signaling. The binding half-life can be controlled by the light intensity [88]. Abbreviations: AsLOV2, the light-oxygen-voltage domain of phototropin 1 derived from Avena sativa; CAR, chimeric antigen receptor; PHYB, phytochrome B; PIF, phytochrome interacting factor; SLB, supported lipid bilayer; TCR, T cell receptor.