Fig. 8: Model of allosteric gating of CNGA3/CNGB3 by cGMP.

The schematic, based on the closed, intermediate, pre-open and open state structures obtained in POPG/POPC nanodiscs, depicts stepwise conformational rearrangements in several key regions during channel opening. The conformational changes triggered by cGMP binding to the β-roll and C-helix of the CNBD propagate to the pore-forming S6 through helices E’F’ of the C-linker and helices A’B’C’D’ of the gating ring, ultimately resulting in the opening of the cavity gate and arginine gate. The sequential movement of different regions is highlighted in red. Blue lines indicate interactions between S4-S5 and helices A’B’.