May play an important role in the energy releasing mechanism in the visual system. By acting as an energy shuttle and/or as an energy reservoir, ARGK can provide both spatial and temporal buffering in delivering energy in sensory cells. ATP + L-arginine = ADP + H(+) + N(omega)-phospho-L-arginine Highest level of expression in the compound eye. Relatively abundant in the brain, the thorax and the antennae. Lowest expression in the ovaries. Belongs to the ATP:guanido phosphotransferase family.