Premium
Cryo‐electron microscopy and three‐dimensional reconstruction of actin filaments
Author(s) -
Trinick J.,
Cooper T.,
Seymour J.,
Egelman E. H.
Publication year - 1986
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1986.tb02728.x
Subject(s) - protein filament , electron microscope , negative stain , substructure , crystallography , microscopy , perpendicular , helix (gastropod) , resolution (logic) , materials science , molecular physics , transmission electron microscopy , optics , cryo electron microscopy , actin , chemistry , biophysics , physics , geometry , biology , composite material , ecology , structural engineering , mathematics , biochemistry , artificial intelligence , snail , computer science , engineering
SUMMARY Actin filaments have been examined by electron microscopy whilst in a frozen‐hydrated state. Filaments embedded in a vitreous water layer are basically similar to those prepared by negative staining and show characteristic helical substructure, where the pitches of the helices are about 70 nm and 6 nm. Variability in spacing between long pitch helix cross‐over points has been observed, which is consistent with intrinsic angular disorder between successive filament subunits. Fourier transforms of the most ordered filaments show four strong layer lines that index as the first, fifth, sixth and seventh orders of a 35 nm repeat. A three‐dimensional helical reconstruction, calculated to a resolution of about 4 nm, shows the individual subunits to be orientated with their long axes roughly perpendicular to the filament axis. Each subunit is somewhat curved and is resolved into two domains. Most connections between successive subunits appear to be made close to the filament axis. We also report on the performance of the specimen holder (Philips PW 5699) used in this work.