Developing a stable full atom molecular dynamics model starting from a cyro-EM structure of a K+ channel bound to regulatory protein and varying PIP2 concentrations to understand regulation

Abstract

Small conductance Ca2+-activated K+ (SK) channels are unique since they are gated solely by changes in intracellular Ca2+ and are known to be upregulated in heart failure and cardiac arrhythmias. SK channels are regulated via the ubiquitous Ca2+ sensing protein, calmodulin (CaM). New evidence suggests that the anionic lipid phosphatidylinositol 4,5-bisphosphate (PIP2) is also essential for the activation for SK channels. Recent cryo-EM structures with a nearly complete tetrameric SK4-CaM complex (PDB: 6CNM, 6CNN, 6CNO) allowed us to generate nearly full-length SK2-CaM homology models (SK2-CaM).