@article {2083, title = {Imaging intracellular fluorescent proteins at nanometer resolution. (With commentary)}, journal = {Science}, volume = {313}, year = {2006}, month = {2006 Sep 15}, pages = {1642-5}, abstract = {

We introduce a method for optically imaging intracellular proteins at nanometer spatial resolution. Numerous sparse subsets of photoactivatable fluorescent protein molecules were activated, localized (to approximately 2 to 25 nanometers), and then bleached. The aggregate position information from all subsets was then assembled into a superresolution image. We used this method{\textendash}termed photoactivated localization microscopy{\textendash}to image specific target proteins in thin sections of lysosomes and mitochondria; in fixed whole cells, we imaged vinculin at focal adhesions, actin within a lamellipodium, and the distribution of the retroviral protein Gag at the plasma membrane.

Commentary: The original PALM paper by myself and my friend and co-inventor Harald Hess, spanning the before- and after-HHMI eras. Submitted and publicly presented months before other publications in the same year, the lessons of the paper remain widely misunderstood: 1) localization precision is not resolution; 2) the ability to resolve a few molecules by the Rayleigh criterion in a diffraction limited region (DLR) does not imply the ability to resolve structures of arbitrary complexity at the same scale; 3) true resolution well beyond the Abbe limit requires the ability to isolate and localize hundreds or thousands of molecules in one DLR; and 4) certain photoactivatable fluorescent proteins (PA-FPs) and caged dyes can be isolated and precisely localized at such densities; yielding true resolution down to \ 20 nm. The molecular densities we demonstrate (105 molecules/m2) are more than two orders of magnitude greater than in later papers that year (implying ten-fold better true resolution) {\textendash} indeed, these papers demonstrate densities only comparable to earlier spectral or photobleaching based isolation methods. We validate our claims by correlative electron microscopy, and demonstrate the outstanding advantages of PA-FPs for superresolution microscopy: minimally perturbative sample preparation; high labeling densities; close binding to molecular targets; and zero non-specific background.

}, keywords = {Actins, Algorithms, Animals, Cell Line, Cell Membrane, Cercopithecus aethiops, COS Cells, Fluorescence, Focal Adhesions, gag, Gene Products, HIV-1, Light, Luminescent Proteins, Lysosomes, Microscopy, Mitochondria, Nanotechnology, Organelles, Photobleaching, Proteins, Pseudopodia, Recombinant Fusion Proteins, Vinculin}, issn = {1095-9203}, doi = {10.1126/science.1127344}, url = {http://www.ncbi.nlm.nih.gov/pubmed/16902090}, author = {Betzig, Eric and Patterson, George H and Sougrat, Rachid and Lindwasser, O Wolf and Olenych, Scott and Bonifacino, Juan S and Davidson, Michael W and Lippincott-Schwartz, Jennifer and Hess, Harald F} }