While all microbial rhodopsins have significant sequence homology to one another, they have no detectable sequence homology to the G-protein-coupled receptor (GPCR) family to which animal visual rhodopsins belong.
Medan alla mikrobiella rodopsiner har signifikant sekvenshomologi till varandra, har de ingen detekterbar sekvens homologi till den G-protein-coupled receptor (GPCR) familjen, till vilken djurs visuella rodopsiner hör.