Chunhonginvestigated the valence selectivity of RyR channels by using atomistic MD simulations, and observed the details of competition between Ca++ and K+ in the extended selectivity filter of RyRs. The presence of Ca++ significantly decreases the K+ conductance, while K+ has little impact on Ca++ permeation, due to the much stronger binding of Ca++ in the highly negatively charged and size-limited luminal vestibule. This is a further application of our recently developed multisite Ca++ model, showing atomistic details of valence selectivity of RyRs that are in good agreement with previous experimental findings and simplified models. The paper can be found here.