Bacteriorhodopsin (bR)

Bacteriorhodopsin is a light-driven proton pump found in the purple membrane of the archaeon Halobacterium salinarum (UniProt: P02945). It consists of a seven-transmembrane protein, bacterio-opsin, and a covalently bound retinal chromophore attached via a Schiff base to a lysine residue (Ernst et al., 2014). Upon the absorption of light, the retinal undergoes photoisomerization from an all-trans to a 13-cis configuration, which triggers a series of conformational changes known as the photocycle (Lanyi, 2004). This process results in the active transport of protons from the cytoplasm to the extracellular space, creating an electrochemical gradient used for ATP synthesis. While not a native human protein, it is a primary model system for studying G protein-coupled receptors (GPCRs) and membrane protein dynamics. In therapeutic research, bacteriorhodopsin and its derivatives are investigated for optogenetic applications, such as restoring light sensitivity in degenerate retinal cells (Busskamp et al., 2010). It is also utilized in biotechnology for optical switching and high-density data storage due to its robust stability and unique photochemical properties.

Other names

Bacterio-opsinPurple membrane proteinRetinal-bound bacterio-opsin

Light-induced photoisomerization of the retinal chromophore from all-trans to 13-cis, driving a conformational change that pumps protons across the cell membrane (Lanyi, 2004; Ernst et al., 2014).