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Review
. 2011 May;137(5):397-403.
doi: 10.1085/jgp.201010546.

Structural studies of ion selectivity in tetrameric cation channels

Amer Alam  1 , Youxing Jiang
Affiliations
Review

Structural studies of ion selectivity in tetrameric cation channels

Amer Alam et al. J Gen Physiol. 2011 May.
No abstract available

PubMed Disclaimer

Figures

Figure 1.
Figure 1.
Structure of KcsA. (A) Overall structure of KcsA, with the front subunit removed for clarity. Selectivity filter (boxed) is colored yellow. Ions in the selectivity filter and cavity are shown as green spheres. M1, outer helix; M2, inner helix; P, pore helix. (B) Zoom-in view of the selectivity filter. The K+ ion in the cavity is surrounded by eight water molecules (red spheres). The four ion-binding sites within the filter are labeled 1–4 from top to bottom.
Figure 2.
Figure 2.
Selectivity filter of MthK. K+ ions in the selectivity filter are shown as green spheres, and the four water molecules at the external entrance are shown as red spheres.
Figure 3.
Figure 3.
Structure of NaK. (A) Overall structure of NaK, with the front subunit removed for clarity. Selectivity filter is colored yellow. Ions in the selectivity filter are shown as green spheres. (B) Zoom-in view of the selectivity filter of NaK in K (green spheres). The water molecules in the vestibule and at the external entrance are shown as red spheres. The two ion-binding sites within the filter are labeled 3 and 4. (C) Zoom-in view of the selectivity filter of NaK in Na (green spheres).
Figure 4.
Figure 4.
Selectivity filter structures of NaK mutants. (A) Partial sequence alignment between NaK, K+ channels (MthK, KcsA, and Shaker), and human CNG channel α subunits (A1–A3). The sequences of NaK2CNG-D and NaK2K mutants are also shown in which the mutated residues are boxed. Residues forming the selectivity filter are shaded orange. (B) Structure of NaK2CNG chimera. The three ion-binding sites within the filter are labeled 2–4 from top to bottom. (C) Structure of the K+-selective NaK2K mutant.
See this image and copyright information in PMC

References

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    1. Alam A., Shi N., Jiang Y. 2007. Structural insight into Ca2+ specificity in tetrameric cation channels. Proc. Natl. Acad. Sci. USA. 104:15334–15339 10.1073/pnas.0707324104 - DOI - PMC - PubMed
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