The invention relates to a monoclonal antibody which binds to octopus rhodopsin and octopus metarhodopsin wherein said monoclonal antibody binds with higher affinity to metarhodopsin than to rhodopsin and does not inhibit rhodopsin-metarhodopsin interconversion upon exposure to blue or red light. The monoclonal antibody binds to a peptide having the sequence Val-Ile-Gly-Arg-Pro-Met-Ala-Ala-Ser-Lys-Lys-Met-Ser. The photochemical reaction of rhodopsin thin layers may be detected using the anti-rhodopsin monoclonal antibodies of the invention.
Anti-octopus rhodopsin monoclonal antibody