Figure 20.

Intracellular calcium concentrations could be perturbed with BL-sensitive photoreceptors. On the one hand, the opening of Ca²⁺-specific CRAC channels in the plasma membrane or the endoplasmic/sarcoplasmic reticulum was gated via interactions with the STIM peptide.^124,304,305 When interleaved with Jα of AsLOV2, the exposure of STIM could be controlled by BL exposure. Alternatively, the STIM epitope was fused to AtCRY2 such that BL-induced clustering resulted in translocation to the membrane and CRAC gating (not shown³⁰⁷). A different strategy was pursued in the construction of a fusion protein between the AsLOV2 photosensor and the calcium-binding calmodulin.³⁰⁹ BL prompted Jα unfolding, destabilization of the calmodulin module and release of bound Ca²⁺ ions.