TEM images of proteins with known structure using OpNS. a) Survey view of a small and asymmetric protein, 53 kDa CETP (dashed circles) by OpNS. b) 30 representative images of CETP particles. c) Two representative images of CETP particles with particle orientation identified by their tapered tip end (N-terminal β-barrel domain) and globular tip end (C-terminal β-barrel domain), d) which is consistent with the CETP structure, obtained from X-ray crystallography (PDB: 2OBD), in size and shape. e) The high-contrast images were used to reconstruct a 3D volume at 1.4 nm resolution. f) Survey view of another protein with known structure, GroEL, and g) 9 representative particles images prepared by OpNS. h) Survey view of a third protein with known structure, proteasome, and i) 9 representative particle images prepared by OpNS. Scale bars: a) 50 nm; e) 3 nm; f) and h) 50 nm. a–e) Reproduced with permission.[162] Copyright 2012, rights managed by Nature Publishing Group; f–i) Reproduced with permission.[181] Copyright 2014, The Authors, published by Journal of Vizualized Experiments (JoVE).