Abstract
Light is one of the most important signals providing critical information to biological systems. Four rhodopsins, bacteriorhodopsin (BR), halorhodopsin (hR), sensory rhodopsin (sR) and phoborhodopsin (pR) exist in archaeal membranes. bR and hR work as a light-driven ion pump. sR and pR work as a photo-sensor of phototaxis, and form signaling complexes in membranes with their respective cognate transducer proteins HtrI (with sR) and HtrII (with pR), through which light signals are transmitted to cytoplasm. In this review, we describe our results on the protein-protein interaction of archaeal rhodopsins/HtrII and the signal transfer reaction by the complexes.
