Structural Foundations of Potassium Selectivity in Channelrhodopsins

Abstract

Recently discovered microbial light-gated ion channels (channelrhodopsins) with a higher permeability for K + than for Na + (potassium-selective channelrhodopsins [kalium channelrhodopsins, or KCRs]) demonstrate an alternative K + selectivity mechanism, unrelated to well-characterized “selectivity filters” of voltage- and ligand-gated K + channels. KCRs can be used for optogenetic inhibition of neuronal firing and potentially for the development of gene therapies to treat neurological and cardiovascular disorders.