Figure 5.

Structure and function of LOV. (A) The light/oxygen/voltage (LOV) domain is composed by a “core” and a helical domain called the Ja helix. Together they sandwich a flavin molecule in dark conditions. Upon light activation the Ja helix undocks. The LOV domain has been harnessed to cage signal peptides or functional domains of enzymes. (B) Organelle transport by LOV (mitochondria). A mitochondria-localized LOV domain caging a small peptide (LOVpep) that upon light exposure is exposed and bound by an engineered PDZ domain (ePDZ). By fusing ePDZ with motor protein kinesin, it is possible to control the translocation of mitochondria along microtubules in the axons of neurons. (C) Light-control on migration: In dark the LOV domain sterically blocks a constitutively-active Rac1. Uncaging Ja helix by light exposes Rac1 to its effector protein, triggering actin filament polymerisation and stimulated cell movement in the direction of the cell's illuminated edge.