Fig 4. FAK mechano-signaling.

A) Rupture force F as a function of the loading rate $\dot{F}$, where F is defined as the maximal force observed during FK-FAK activation (arrow in the inset). Light grey dots represent individual rupture forces F observed in our membrane-free FPMD simulations. Dark grey dots represent their averages (for each loading rate $\dot{F}$). The solid line shows the mean rupture force 〈F〉 predicted by the BSK model [45] for ΔG = 28.5 k _B T, x _b = 0.86 nm, and D = 6.6 × 10⁶ nm²/s. A fit with the HS [44] model yields similar model parameters (not shown). Dashed lines show the variation of the rupture forces predicted by the BSK model (2 standard deviations, see S1 Text for a detailed analysis). Pulling membrane-bound FK-FAK diagonally yielded similarly large rupture forces (green dots). Vertical pulling resulted in significantly lower rupture forces (pink dots), as this direction promotes the less resistant zipper-like dissociation mechanism described in S4B and S4C Fig) Time at which 50% of inactive FAK (B) and GDP-bound Ras protein (C) are consumed, under varying external force. Times obtained for three sets of parameters (1 to 3) corresponding to the three fits presented in S6 Fig.