How did the experiments of Frye and Edidin support the hypothesis that some proteins could move within cell membrane?

Answer 1

Frye and Edidin demonstrated that proteins are free to diffuse across the plane of the membrane. They did this by first covalently attaching fluorescent labels of two different colors (blue and red in this animation) to antibodies specific for proteins exposed on the outer surface of mouse and human cells. The human cells were exposed to the fluorescently labeled anti-human antibody and the mouse cells were exposed to the fluorescently labeled anti-mouse antibody. The antibodies bound to their antigenic determinents, thus labeling the human and mouse cells with either blue or red spots. The labeled cells were mixed and exposed to the Sendai virus which induces the cells to fuse together forming a hybrid cells with two nuclei. Immediately after the fusion event, two hemispheres of colored proteins were visible that showed where the mouse and human proteins resided. However, during the next 40 minutes the human and mouse proteins were seen to diffuse across the plane of the membrane until the distribution of human and mouse proteins was completely random. This experiment has been interpreted and clearly demonstrating the lateral diffusion of proteins across the plane of the membrane.