Structure and architecture of the assembling fibronectin fibril. A representative simulation structure and architecture are shown at 0.5 and 5 h. (A) The Hookean spring network connections along the z axis are shown: elastic FN Type III domains (black), FN-FN binding (red), inelastic FN Type I and II domains (blue), and integrin binding (green) are shown. The FA complex is illustrated in the intracellular space as spanning the range of FN-bound integrins. (B) The FN fibril cross section in the x,y plane is shown, with FN-FN connections (red). Interior and exterior FN molecules are shown in black and green, respectively. (C) The 3D FN fibril architecture is shown. Parameters: ksub = 1000 pN/nm. To see this figure in color, go online.