Use of caged fluorochromes to track macromolecular movement in living cells

One way to visualize and track the movement of macromolecules in the living cell is to follow their movement after tagging the molecule with a 'caged' or chemically masked fluorochrome. The fluorochrome does not fluoresce unt il the caging group is released by spot photoactivation, and the bright flu orescent signal can then be tracked as it moves into the dark surrounding a rea of the cell. When coupled with rapid imaging microscopy, it is possible to measure rates of movement as fast as macromolecular diffusion. This art icle describes the use of photoactivatable fluorochromes to track the intra cellular movement of boat proteins and nucleic acids and to track cell line ages.