FRAP: Automatic Analysis of Lipid Data

The simulation above depicts the planar movement of fluorescently labeled lipid and protein in the plasma membrane of a cultured cell.  Start the simulation using the upper-left button.  Lipid fluorescence within the target circle (the number of red particles) is plotted every 5 sec and a green curve is continuously fitted to the average of these data.  At 55 sec the target is bleached and its fluorescence drops to zero.  Subsequently, target fluorescence recovers and data continue to be plotted every 5 sec without curve-fitting.  After 20 sec or so, fit the recovery data with a curve using the upper-right "Curve Fit" button, which may then be used periodically to refit new data.  Why is the curve shaped like a hyperbola?  Use the "Reset" button to restart the experiment.

Do the membrane protein behave differently than those viewed earlier in the model bilayer FRAP experiment?  How so?  Turn the page to analyze protein data from a similar FRAP experiment.