Hydrogen-bonding network at the cytoplasmic region of a light-driven sodium pump rhodopsin KR2

Light-driven sodium-pumping rhodopsins are able to actively transport sodium ions. Structure/function studies of Krokinobacter eikastus rhodopsin 2 (KR2) identified N61 and G263 at the cytoplasmic surface constituting the "Ion-selectivity filter" for sodium ions, while retinal Schiff base acts as the light "Switch and Gate" for transport of sodium ions. Q123 is located between the two regions, and plays an important role for the pump function,...