Structure of the transmembrane regions of a bacterial cyclic nucleotide-regulated channel.
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Clayton GM, Altieri S, Heginbotham L, Unger VM, Morais-Cabral JH
Structure of the transmembrane regions of a bacterial cyclic nucleotide-regulated channel.
Proc Natl Acad Sci U S A. 2008 Feb 5;105(5):1511-5. doi: 10.1073/pnas.0711533105. Epub 2008 Jan 23.
- PubMed ID
- 18216238 [ View in PubMed]
- Abstract
The six-transmembrane helix (6 TM) tetrameric cation channels form the largest ion channel family, some members of which are voltage-gated and others are not. There are no reported channel structures to match the wealth of functional data on the non-voltage-gated members. We determined the structure of the transmembrane regions of the bacterial cyclic nucleotide-regulated channel MlotiK1, a non-voltage-gated 6 TM channel. The structure showed how the S1-S4 domain and its associated linker can serve as a clamp to constrain the gate of the pore and possibly function in concert with ligand-binding domains to regulate the opening of the pore. The structure also led us to hypothesize a new mechanism by which motions of the S6 inner helices can gate the ion conduction pathway at a position along the pore closer to the selectivity filter than the canonical helix bundle crossing.