A–D. Examples showing 3.8-nm thick slices through
three-dimensional cyro-tomograms.
A. Region near the leading edge of a wild-type cell showing actin
filaments running at different angles and branch junctions (arrowhead).
B. Region in a filopodium of a wild-type cell showing parallel
filaments separated by variable distances and with cross-linkers of different
sizes (arrowheads).
C. Region of an FLP in an ARPC3−/− mutant
fibroblast showing closely packed parallel bundles of filaments with different
size cross-linkers (arrowheads).
D. Slice through a three-dimensional cryo-tomogram of a bundle of
purified actin filaments cross-linked by fascin. The arrowhead points at a
fascin cross-link between the actin filaments. Bar is 200 nm and applies to
A–D.
E–F. Features in the Interior region of wild-type (E) and
ARPC3−/− (F) fibroblasts. Various vesicular
structures (V) with different content and attachements are visible. Tentative
intermediate filaments (IF) and ribosomes (R) can also be identified. The actin
structures visible (A) are reminiscent of those at the cell edge. They are more
loosely organised in the wild-type cells. 7.6-nm slices are shown, the bar is
500 nm.