A reduced mechanical model for cAMP-modulated gating in HCN channels

Figure 1. Magnitude of displacement of the Cα atoms of one HCN subunit after LRT. The y-axis is in arbitrary units.

Figure 2. HCN4 tetramer, one chain is shown in turquoise in a cartoon representation. Arrows represent the displacement after LRT force application to the cAMP binding pocket residues of all four subunits simultaneously.

Figure 3. from LRT compared to a linear combination of three eigenvectors (, cyan) with the highest overlap with (red): no. 8, no. 13 and no. 10 (overlap: 0.95). Eigenvectors were derived from a singular value decomposition of the Hessian matrix of the system. Plotted vectors were scaled to the same magnitude for better comparability.

Figure 4. per residue (blue arrows) in one monomer (purple) from LRT upon an external electrical field across the membrane.

Figure 5. Transmembrane region and part of the C-linker of two neighboring subunits of HCN4 (white and gray). The contacts that cause significant change of displacement when switched off are indicated by cylinders. Intra-subunit contacts are drawn in red (282–295, 269–309, 322–334, 286–381, 266–396, 266–399, 395–407, 395–408, 402–560, 403–561), inter-subunit contacts in yellow (430–277, 466–278, 466–282, 438–284, 438–286, 424–407, 497–422, 331–545).

Figure 6. C-terminal domain with part of the C-linker and CNBD. The contacts that cause significant change of displacement when switched off are indicated by cylinders (642–658, 670–710, 649–713). Colors as in Fig. 5.