beta-carotene 15,15'-monooxygenase, Brp/Blh family
This integral membrane protein family includes Brp (bacterio-opsin related protein) and Blh (Brp-like protein). Bacteriorhodopsin is a light-driven proton pump with a covalently bound retinal cofactor that appears to be derived beta-carotene. Blh has been shown to cleave beta-carotene to product two all-trans retinal molecules. Mammalian enzymes with similar enzymatic function are not multiple membrane spanning proteins and are not homologous.