Abstract
Phototropin (phot) is a blue light photoreceptor in plants that mediates phototropism, chloroplast relocation, stomata opening. A phot molecule has two photoreceptive domains named LOV1 and LOV2 in the C-terminal half and a Ser/Thr kinase domain (KD) at the N-terminus. Phot is thought to be a light-regulated protein kinase, In the present talk, we will introduce newest figures of its functional domain structures, photoreaction and accompanying conformational changes, and regulation of the kinase including our recent results. LOV2, a major molecular switch, prohibits constitutive activity of phot kinase in the dark. Blue light initiates a unique cyclic photoreaction in the LOV domains that induces conformational changes in the LOV2 core and its linker region to KD. This results in dissociation of the LOV2 from KD and brings activation of the kinase. While, LOV1 acts as a dimerization site in phot molecules.
