(a) A space-filled model of CyPPA docked into the binding pocket. Molecular docking and MD simulation were performed to dock CyPPA into the PHU binding pocket based on the structure of PHU in the CaM-CaMBD2-a complex. (b) A space-filled model of CyPPA docked into the binding pocket with the A477V/L480M mutation (green). Molecular docking and MD simulations were performed to introduce the A477V/L480M mutation and then docking of CyPPA. Note that the A477V/L480M mutation is predicted to force CyPPA to adopt a different conformation in the pocket. (c) The A477V/L480M mutation on the effect of CyPPA. Responses of the A477V/L480M mutant, from an inside-out patch, to sequential application of solutions containing (1) 0 Ca2+, (2) 200 nM Ca2+, (3) 100 μM CyPPA with 200 nM Ca2+, (4) 10 μM NS309 with 200 nM Ca2+ and (5) 0 Ca2+. The current amplitudes were measured at −90 mV. Note that CyPPA, at 100 μM, barely potentiates the mutant channel activity. (d) Responses of SK2 channels, WT (n = 6), V418T (n = 3) and A477V/L480M (n = 5), to increasing concentrations of CyPPA. 200 nM Ca2+ was present in all CyPPA solutions. Note that there is little response from the A477V/L480M mutant at the CyPPA concentration range tested. All data are mean ± s.e.m.