Paul R. Selvin

Point accumulation for imaging in nanoscale topography (PAINT) is a single‐molecule technique for super‐resolution microscopy, which uses exchangeable single stranded DNA oligos or peptide‐pairs to create blinking phenomenon and achieves ≈5–25 nanometer resolution. Here, it is shown that by transfecting the protein‐of‐interest with a docker‐coil, rather than by adding the docker externally—as is the norm when using DNA tethers or antibodies as dockers—similar localization can be achieved, ≈10 nm. However, using a transfected docker has several experimental advances and simplifications. Most importantly, it allows Peptide‐PAINT to be applied to transfected live cells for imaging surface proteins in mammalian cells and neurons under physiological conditions. The enhanced resolution of Peptide‐PAINT is also shown for organelles in fixed cells to unravel structural details including ≈40‐nm and ≈60‐nm axial repeats in vimentin filaments in the cytoplasm, and fiber shapes of sub‐100‐nm histone‐rich regions in the nucleus.