Noun
bacteriorhodopsin (plural bacteriorhodopsins)
(biochemistry) Any of several related purple photosynthetic proteins, found in halobacteria, that act as proton pumps
It is similar to and probably originated from bacteriorhodopsin (see below under archaea). Source: Internet
Archaea Halobacteria use the pigment bacteriorhodopsin which acts directly as a proton pump when exposed to light. Source: Internet