Abstract
We have probed internal and external accessibility of S4 residues to the membrane-impermeant thiol reagent methanethiosulfonate- ethyltrimethylammonium (MTSET) in both open and closed, cysteine-substituted Shaker K+ channels. Our results indicate that S4 traverses the membrane with no more than 5 amino acids in the closed state, and that the distribution of buried residues changes when channels open. This change argues for a displacement of S4 through the plane of the membrane in which an initially intracellular residue moves to within 3 amino acids of the extracellular solution. These results demonstrate that the putative voltage-sensing charges of S4 actually reside in the membrane and that they move outward when channels open. We consider constraints placed on channel structure by these results.
Original language | English (US) |
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Pages (from-to) | 387-397 |
Number of pages | 11 |
Journal | Neuron |
Volume | 16 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1996 |
Externally published | Yes |
ASJC Scopus subject areas
- Neuroscience(all)