Light-induced conformational change of octopus rhodopsin as detected by a spin label method

Abstract

Summary Using a spin-labeling technique, the light-induced conformational changes in proteins were detected in microvillar membranes of photoreceptor cells of octopus as well as in digitonin extract of the membrane. The change in EPR spectrum of the spin-label was induced with blue light (wavelengths around 420 nm) and the change was reversed with orange light (wavelengths longer than 580 nm). It is concluded that these reversible spectral changes correspond to the differences in the structure of the protein moiety between rhodopsin and metarhodopsin.