Ion channels provide passageways through which charged ions can cross cellular membranes. Some ion channels allow only one type of ion through, while others, called nonselective ion channels, allow multiple types of ions to cross. IPiB graduate student Adam Lewis used nuclear magnetic resonance (NMR) spectroscopy to study how the NaK ion channel adapts its structure to conduct multiple types of ions.
Lewis’ research supports at least one theoretical hypothesis and provides a possible explanation as to why Na+ does not efficiently permeate through NaK in theoretical simulations. Lewis found that the “selectivity filter” in NaK ion channels is more flexible than the selectivity filter in K+-selective ion channels. He also found that the selectivity filter in NaK ion channels has multiple structural states, not all of which are captured in X-ray crystal structures. Flexibility and multiple structural states are in part what make NaK ion channels permeable to both sodium and potassium ions.
“Ion channels are an important class of proteins…Defects in ion channels can cause diseases like cardiac arrhythmias or epilepsy,” Lewis, a member of the Henzler-Wildman Lab, says. “An advantage of using nuclear magnetic resonance spectroscopy is that we can characterize both the structure and also the internal dynamics of proteins.”
To learn more about his research, attend Lewis’ Thesis Defense on Tuesday, December 14 in Room 1211 Biochemical Sciences.