Abstract
LOV (Light-Oxygen-Voltage sensing) domains form a subfamily of PAS domain. A major LOV protein, phototropin (phot), has two LOV domains named LOV1 and LOV2. Although the reported crystal structures of LOV1 and LOV2 are almost identical, they play divergent functions. LOV1 has a minor contribution to the phenotype expression or the regulation of kinase activity, while, acts as a dimerization site. In contrast, LOV2 functions as a main light-regulated molecular switch. Structural changes that were not detected by crystallography and the different photochemical properties may explain the difference in the functions between the two LOV domains. The other major LOV proteins are the FKF1 families that have only one LOV domain. Their LOV domains have 9 extra amino acids and their photochemistries are much different from those of phot LOV, that may be correlated with their functions.
