Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Proc Natl Acad Sci U S A
2005 Apr 05;10214:5020-5. doi: 10.1073/pnas.0501051102.
Show Gene links
Show Anatomy links
S3b amino acid residues do not shuttle across the bilayer in voltage-dependent Shaker K+ channels.
Gonzalez C, Morera FJ, Rosenmann E, Alvarez O, Latorre R.
???displayArticle.abstract???
In voltage-dependent channels, positive charges contained within the S4 domain are the voltage-sensing elements. The "voltage-sensor paddle" gating mechanism proposed for the KvAP K+ channel has been the subject of intense discussion regarding its general applicability to the family of voltage-gated channels. In this model, the voltage sensor composed of the S3b and the S4 segment shuttles across the lipid bilayer during channel activation. Guided by this mechanism, we assessed here the accessibility of residues in the S3 segment of the Shaker K+ channel by using cysteine-scanning mutagenesis. Mutants expressed robust K+ currents in Xenopus oocytes and reacted with methanethiosulfonate ethyltrimethylammonium in both closed and open conformations of the channel. Because Shaker has a long S3-S4 linker segment, we generated a deletion mutant with only three residues to emulate the KvAP structure. In this short linker mutant, all of the tested residues in the S3b were accessible to methanethiosulfonate ethyltrimethylammonium in both closed and open conformations. Because the S3b moves together with the S4 domain in the paddle model, we tested the effects of deleting two negative charges or adding a positive charge to this region of the channel. We found that altering the S3b net charge does not modify the total gating charge involved in channel activation. We conclude that the S3b segment is always exposed to the external milieu of the Shaker K+ channel. Our results are incompatible with any model involving a large membrane displacement of segment S3b.
Aggarwal,
Contribution of the S4 segment to gating charge in the Shaker K+ channel.
1996, Pubmed,
Xenbase
Aggarwal,
Contribution of the S4 segment to gating charge in the Shaker K+ channel.
1996,
Pubmed
,
Xenbase Ahern,
Specificity of charge-carrying residues in the voltage sensor of potassium channels.
2004,
Pubmed Almers,
Gating currents and charge movements in excitable membranes.
1978,
Pubmed Baker,
Three transmembrane conformations and sequence-dependent displacement of the S4 domain in shaker K+ channel gating.
1998,
Pubmed Bell,
Changes in local S4 environment provide a voltage-sensing mechanism for mammalian hyperpolarization-activated HCN channels.
2004,
Pubmed
,
Xenbase Bezanilla,
Voltage sensor movements.
2002,
Pubmed Cha,
Atomic scale movement of the voltage-sensing region in a potassium channel measured via spectroscopy.
1999,
Pubmed Durell,
Models of the structure and voltage-gating mechanism of the shaker K+ channel.
2004,
Pubmed Elliott,
Molecular mechanism of voltage sensor movements in a potassium channel.
2004,
Pubmed
,
Xenbase Gandhi,
The orientation and molecular movement of a k(+) channel voltage-sensing domain.
2003,
Pubmed
,
Xenbase Gandhi,
Molecular models of voltage sensing.
2002,
Pubmed Gonzalez,
Periodic perturbations in Shaker K+ channel gating kinetics by deletions in the S3-S4 linker.
2001,
Pubmed
,
Xenbase Gonzalez,
Modulation of the Shaker K(+) channel gating kinetics by the S3-S4 linker.
2000,
Pubmed
,
Xenbase Horn,
How ion channels sense membrane potential.
2005,
Pubmed Jiang,
X-ray structure of a voltage-dependent K+ channel.
2003,
Pubmed Jiang,
The principle of gating charge movement in a voltage-dependent K+ channel.
2003,
Pubmed Lainé,
Atomic proximity between S4 segment and pore domain in Shaker potassium channels.
2003,
Pubmed
,
Xenbase Larsson,
Transmembrane movement of the shaker K+ channel S4.
1996,
Pubmed
,
Xenbase Nguyen,
Movement and crevices around a sodium channel S3 segment.
2002,
Pubmed Noceti,
Effective gating charges per channel in voltage-dependent K+ and Ca2+ channels.
1996,
Pubmed
,
Xenbase Schönherr,
Conformational switch between slow and fast gating modes: allosteric regulation of voltage sensor mobility in the EAG K+ channel.
2002,
Pubmed
,
Xenbase Seoh,
Voltage-sensing residues in the S2 and S4 segments of the Shaker K+ channel.
1996,
Pubmed
,
Xenbase Shrivastava,
A model of voltage gating developed using the KvAP channel crystal structure.
2004,
Pubmed Sigg,
Total charge movement per channel. The relation between gating charge displacement and the voltage sensitivity of activation.
1997,
Pubmed Starace,
Histidine scanning mutagenesis of basic residues of the S4 segment of the shaker k+ channel.
2001,
Pubmed
,
Xenbase Starace,
A proton pore in a potassium channel voltage sensor reveals a focused electric field.
2004,
Pubmed Swartz,
Towards a structural view of gating in potassium channels.
2004,
Pubmed Taglialatela,
Novel voltage clamp to record small, fast currents from ion channels expressed in Xenopus oocytes.
1992,
Pubmed
,
Xenbase Wang,
Effect of cysteine substitutions on the topology of the S4 segment of the Shaker potassium channel: implications for molecular models of gating.
1999,
Pubmed
,
Xenbase Yang,
Molecular basis of charge movement in voltage-gated sodium channels.
1996,
Pubmed Yusaf,
Measurement of the movement of the S4 segment during the activation of a voltage-gated potassium channel.
1996,
Pubmed
,
Xenbase Zagotta,
Shaker potassium channel gating. II: Transitions in the activation pathway.
1994,
Pubmed
,
Xenbase
