Bacterial rhodopsins

Bacterial rhodopsins are a family of bacterial opsins. They are retinal-binding proteins that provide light-dependent ion transport and sensory functions to a family of halophilic and other bacteria. They are integral membrane proteins with seven transmembrane helices, the last of which contains the attachment point for retinal (a conserved lysine).

The proteins from halobacteria include bacteriorhodopsin and archaerhodopsin, which are light-driven proton pumps; halorhodopsin, a light-driven chloride pump; and sensory rhodopsin, which mediates both photoattractant (in the red) and photophobic (in the ultra-violet) responses. Proteins from other bacteria include proteorhodopsin.