Gating Rings Formed by RCK Domains: Keys to Gate Opening

摘要

Despite advances in elucidating the structural basis of ion permeation and pore block, the structural and mechanistic basis for regulating ion channel gating has remained a more elusive problem. For the voltage-dependent K~+ channel superfamily, two major categories of signal, voltage and ligand, are known to regulate gating. Progress on the structural elements involved in gating regulation have been aided immensely by the fact that the key gating regulators, voltage sensors and ligand-binding domains, are largely modular components that are "simply" appended to the basic minimal two transmembrane (2TM) K~+ channel pore motif. Nevertheless, one impediment to the structural understanding of channel gating mechanisms is that the bacterial channels most amenable to full structural determination have not proven as favorable for the required functional studies of the allosteric regulation of channel gating. An article from the laboratory of Youxing Jiang in the current issue of the Journal (see Li et al. on p. 109) suggests that, at least for the Ca~(2+)-activated MthK channel, this situation is about to change.