In the 1960s, a light driven proton pump was discovered in Halobacterium salinarum, and called Bacteriorhodopsin. Over the following years, there were various studies of the membrane of H. salinarum to determine the mechanism of these light-driven proton pumps.
In 1988, another Manabu Yoshidas group at Osaka University reported a novel light-sensitive proton pump from a strain of Halobacterium' which they termed Archaerhodopsin. A year later, the same group reported isolating the gene that encodes Archaerhodopsin.