Six transmembrane segments, S1–S6, cluster around the central pore-forming region in voltage-gated K+ channels. To investigate the structural characteristics of the S2 segment in the Shaker K+ channel, we replaced each residue in S2 singly with tryptophan (or with alanine for the native tryptophan). All but one of the 23 Trp mutants expressed voltage-dependent K+ currents in Xenopus oocytes. The effects of the mutations were classified as being of low or high impact on channel gating properties. The periodicity evident in the effects of these mutations supports an α-helical structure for the S2 segment. The high- and low-impact residues cluster onto opposite faces of a helical wheel projection of the S2 segment. The low-impact face is also tolerant of single mutations to asparagine. All results are consistent with the idea that the low-impact face projects toward membrane lipids and that changes in S2 packing occur upon channel opening. We conclude that the S2 segment is a transmembrane α helix and that the high-impact face packs against other transmembrane segments in the functional channel.
Helical Structure and Packing Orientation of the S2 Segment in the Shaker K+ Channel
S. A. Monks,D. Needleman,Christopher Miller
Published 1999 in The Journal of General Physiology
ABSTRACT
PUBLICATION RECORD
- Publication year
1999
- Venue
The Journal of General Physiology
- Publication date
1999-03-01
- Fields of study
Biology, Medicine, Physics
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
- No claims are published for this paper.
CONCEPTS
- No concepts are published for this paper.
REFERENCES
Showing 1-29 of 29 references · Page 1 of 1