Lateral Diffusion of Visual Pigment in Photoreceptor Disk Membranes

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Science  02 Aug 1974:
Vol. 185, Issue 4149, pp. 457-459
DOI: 10.1126/science.185.4149.457


Visual pigment molecules are found to move transversely, but not longitudinally, in both rod and cone outer segments of mud puppy and frog. This is consistent with the idea that they are immersed in a two-dimensional fluid disk membrane. The diffusion coefficient for the motion is about 5 x 10-9 square centimeters per second at 20°C, corresponding to a root-mean-square molecular displacement of 0.3 micrometer in 1 second.