PT - JOURNAL ARTICLE AU - Veronica Pessino AU - Rose Citron AU - Siyu Feng AU - Bo Huang TI - Covalent protein labeling by SpyTag-SpyCatcher in fixed cells for super-resolution microscopy AID - 10.1101/125013 DP - 2017 Jan 01 TA - bioRxiv PG - 125013 4099 - http://biorxiv.org/content/early/2017/05/14/125013.short 4100 - http://biorxiv.org/content/early/2017/05/14/125013.full AB - Labeling proteins with high specificity and efficiency is a fundamental prerequisite for microscopic visualization of subcellular protein structures and interactions. While the comparatively small size of epitope tags makes them less perturbative to fusion proteins, they require the use of large antibodies that often limit probe accessibility and effective resolution. Here we use the covalent SpyTag-SpyCatcher system as an epitope-like tag for fluorescent labeling of intracellular proteins in fixed cells for both conventional and super-resolution microscopy. We have also applied this method to endogenous proteins via gene editing, demonstrating its high labeling efficiency and capability for isoform-specific labeling.