Download MendeleyIonic interactions of Ba2+ blockades in the MthK K+ channel
Guo, R., Zeng, W., Cui, H., Chen, L., Ye, S.(2014) J Gen Physiol 144: 193-200
- PubMed: 25024268
- DOI: https://doi.org/10.1085/jgp.201411192
- Primary Citation of Related Structures:
4QE7, 4QE9 - PubMed Abstract:
The movement and interaction of multiple ions passing through in single file underlie various fundamental K(+) channel properties, from the effective conduction of K(+) ions to channel blockade by Ba(2+) ions. In this study, we used single-channel electrophysiology and x-ray crystallography to probe the interactions of Ba(2+) with permeant ions within the ion conduction pathway of the MthK K(+) channel. We found that, as typical of K(+) channels, the MthK channel was blocked by Ba(2+) at the internal side, and the Ba(2+)-blocking effect was enhanced by external K(+). We also obtained crystal structures of the MthK K(+) channel pore in both Ba(2+)-Na(+) and Ba(2+)-K(+) environments. In the Ba(2+)-Na(+) environment, we found that a single Ba(2+) ion remained bound in the selectivity filter, preferably at site 2, whereas in the Ba(2+)-K(+) environment, Ba(2+) ions were predominantly distributed between sites 3 and 4. These ionic configurations are remarkably consistent with the functional studies and identify a molecular basis for Ba(2+) blockade of K(+) channels.
Organizational Affiliation:
Life Sciences Institute and Innovation Center for Cell Biology, Zhejiang University, Hangzhou 310058, China.
