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. Author manuscript; available in PMC: 2013 Feb 1.
Published in final edited form as: Nat Cell Biol. 2012 Jul 1;14(8):874–881. doi: 10.1038/ncb2533

Figure 5. External push and internal pull forces applied to local PM sites recruit N-BAR domains to inward curved membrane.

Figure 5

(a) Scanning Electron micrographs depicting membrane deformation at the leading edge. For better visualization, a magnification of a selected region (white box, bottom) depicting a lamellipodium is shown (top). (b) TEM of 3T3 cell parallel to the glass plane indicating actin filaments pulling at the PM as a source of plasma deformation. For better visualization the ends of individual actin cables are highlighted in red. (c) N-BAR domain of Nadrin2 accumulates on membrane deformations at the leading edge. 3T3 cells were transfected with fluorescently tagged N-BAR domain of Nadrin2, fixed and incubated with primary antibody directed against the fluorescent tag. Enrichment of Immunogold particles to curved sites was measured (n= 15 cells) and compared to adjacent regions within the same image. Note that gold-conjugated secondary antibody is significantly enriched on inward curved membrane sites (graph, bottom). (d) Different types of force-dependent membrane deformations recruit N-BAR domain proteins. N-BAR domain proteins (red) sense positive (inward) membrane curvature induced by external force such as the Nanocone substrate (left), during MyosinII triggered actin contraction (middle), and during endocytosis (right). Error bars represent s.e.m. of the mean value; ** P < 0.01.