Effect of SH reagents on rod photoresponse of isolated frog retina.

Several SH reagents, N-ethylmaleimide (NEM), p-chloromercuribenzoic acid (PCMB), p-chloromercuribenzene sulphonate (PCMBS) and monoiodoacetic acid (MIAA) changed the wave form and the peak of the amplitude of the photoresponse remarkably. The effects of amino group modifying reagents, ethyl acetimidate (EA) and isethinyl acetimidate (ITA) on photoresponse were very slight. The possibility of a SH protein as cGMP-sensitive cation channel protein is discussed.