PMC

The most probable lamella structure of (AG)₁₅ with silk II structure by assuming the presence of two turn parts at the 11th and 19th positions exclusively.

Overall model and example electrostatic potential maps for the proteinase K structures determined using electron diffraction data. (A) The models for the structures determined from nanocrystals (cyan) and the structures determined from lamella with the 20 μm (magenta) and 50 μm (green) condenser apertures are shown aligned by C-alpha residues in cartoon representation with the Ca2+ ion depicted as a sphere. (B–D) A section of the electrostatic potential maps around the disulfide bridge linking residues Cys34 and Cys123 is shown with the 2mFo – Fc maps contoured at 1.0 σ above the mean for the nancrystals (B), 20 μm C2 aperture lamella dataset (C) and the 50 μm C2 aperture lamella dataset (D).

Model of MT arrangement and turnover in the lamella and lamellipodia of migrating newt lung epithelial cells. Thick lines represent MTs; dotted lines, the border between the lamella and lamellipodia; thin arrows, MT growth or shortening; arrowheads, sites of MT breakage; thick arrows, the direction of retrograde flow; dotted area, the putative zone of MT breakage at the base of the lamella; and circles, the centrosome. The numbers in the diagram refer to findings and hypotheses from this study. The cell is migrating to the right. 1, MTs in the lamella oriented perpendicular to the leading edge extend to the base of the lamellipodia, exhibit frequent and short dynamic instability, and show little net change in length. 2, Parallel MTs within the lamellipodia undergo catastrophe less often and exhibit net growth. 3, Parallel MTs and photoactivated marks on perpendicular MTs in the lamella (stars) move continuously towards the cell center at ∼0.4 μm/min. 4, F-actin (beaded lines) crosslinked to MTs is postulated to be moved rearward by myosin, which is bound to an unknown stationary structure (question mark) in the lamella. 5, MT breakage occurring at sites of local MT buckling. 6, Free minus ends formed by breakage are specifically capped (asterisks). 7, Treadmilling of MTs by net plus end growth and net minus end shortening. 8, <25% of all MTs in the cell are bound at their minus ends to the centrosome. 9, Cytoplasmic dynein bound to a membranous organelle (question mark) or other MT crosslinking proteins, are proposed to organize noncentrosomal MTs in the lamella.

(a) tree-like structure, incident light, reflected light, incident angle α, and viewing angle β; and (b) evolving the model from a multilayer to a tree-like structure by incorporating three parameters: ΔR (ridge width) = 60 nm, ΔT (lamella taper) = 10 nm, and ΔL (lamella distribution) = 0 nm, 100 nm, 0 nm, 100 nm, ….; (c) the boundary condition in the vertical direction is absorbing (perfectly matched layer, PML), and the boundary condition in the horizontal direction is periodic (periodic boundary condition, PBC).