Photoswitchable Fluorescent Proteins for Superresolution Fluorescence Microscopy Circumventing the Diffraction Limit of Light

In the last two decades, fluorescent proteins became an indispensable tool to noninvasively label a protein in living cells. The discovery of photoswitchable fluorescent proteins expanded the applications of the fluorescent proteins to techniques such as molecular tracking and highlighting on a microscope. Recently, a new microscopic modality to achieve a superresolution circumventing the diffraction limit of light (photoactivated localization microscopy, PALM) has been developed based on the photoswitchable fluorescent proteins. Here we introduce a basic protocol of PALM through the visualization of actin bundles with superresolution.