Ion binding in a potassium ion channel in membrane bilayers is studied by NMR, yielding insights into channel inactivation. At high potassium the selectivity filter is in a conductive form, and at low potassium it collapses into a long-lived nonconductive structure with reduced ion occupancy. New solid-state NMR methods are applied to full length wild type channel and to the inactivation-less mutants, to test the hypothesis that an important channel-inactivation process has as its central step the evacuation of ions from the selectivity filter.  To gain more insight into the role of the E71A mutation, we also characterize the protonation state of E71 and its hydrogen bond partner.  We also show that ion affinity is strongly allosterically coupled to pH triggered opening of the channel.

Functional studies of an ion channel by NMR in native membranes

251st National Meeting (2016)

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