Figure 5.

Diagrammatic representation of FRAP. A fluophore (eg, GFP) is covalently attached to the molecule of interest. The fluorescently tagged molecules are visualised using a microscope and photobleached. Now there is a black area filled with photobleached molecules surrounded by fluorescently tagged molecules that have not been photobleached. If these molecules are able to diffuse, this will cause the fluorescent area to become a little less bright, and the blackened area will gradually increase in brightness as fluorescent molecules migrate into this area. A) GFP tagged molecules from outside the marked area moving in after photobleaching of selected area. B) No movement of GFP tagged molecules into selected region after initial photobleach.