PMID- 23761630
OWN - NLM
STAT- MEDLINE
DCOM- 20131024
LR  - 20200930
IS  - 1522-1563 (Electronic)
IS  - 0363-6143 (Linking)
VI  - 305
IP  - 4
DP  - 2013 Aug 15
TI  - The neutral, hydrophobic isoleucine at position I521 in the extracellular S4 
      domain of hERG contributes to channel gating equilibrium.
PG  - C468-78
LID - 10.1152/ajpcell.00147.2013 [doi]
AB  - The human ether-a-go-go related (hERG) potassium channel has unusual functional 
      characteristics in that the rates of channel activation and deactivation are much 
      slower than inactivation, which is attributed to specific structural elements 
      within the NH2 terminus and the S1-S4 voltage-sensing domains (VSD). Although the 
      charged residues in the VSD have been extensively modified and mutated as a 
      result, the role and importance of specific hydrophobic residues in the S4 has 
      been much less explored in studies of hERG gating. We found that charged, but not 
      neutral or hydrophobic, amino acid substitution of isoleucine 521 at the outer 
      end of the S4 transmembrane domain resulted in channels activating at much more 
      negative voltages associated with a marked hyperpolarization of the 
      conductance-voltage (G-V) relationship. The contributions of different 
      physicochemical properties to this effect were probed by chemical modification of 
      channels substituted with cysteine at position I521. When positively charged 
      reagents including tetramethyl-rhodamine-5-maleimide (TMRM), 
      1-(2-maleimidylethyl)-4-[5-(4-methoxyphenyl)oxazol-2-yl] pyridinium 
      methane-sulfonate (PyMPO), [2-(trimethylammonium)ethyl] methanethiosulfonate 
      chloride (MTSET), and 2-aminoethyl methanethiosulfonate hydrobromide (MTSEA) were 
      bound to the cysteine, I521C channels activated at more negative membrane 
      potentials. To examine the contributions to hERG gating of other residues at the 
      outer end of S4 (520-528), we performed a cysteine scan combined with MTSET 
      modification. Only L520C, along with I521C, shows a substantial hyperpolarizing 
      shift of the G-V relationship upon MTSET modification. The data indicate that the 
      neutral, hydrophobic residue I521 at the extracellular end of S4 is critical for 
      stabilizing the closed conformation of the hERG channel relative to the open 
      state and by comparison with Shaker supports the alignment of hERG I521 with 
      Shaker L361.
FAU - Dou, Ying
AU  - Dou Y
AD  - Department of Anesthesiology, Pharmacology and Therapeutics, University of 
      British Columbia, Vancouver, British Columbia, Canada.
FAU - Goodchild, Samuel J
AU  - Goodchild SJ
FAU - Velde, Robert Vander
AU  - Velde RV
FAU - Wu, Yue
AU  - Wu Y
FAU - Fedida, David
AU  - Fedida D
LA  - eng
GR  - Canadian Institutes of Health Research/Canada
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130612
PL  - United States
TA  - Am J Physiol Cell Physiol
JT  - American journal of physiology. Cell physiology
JID - 100901225
RN  - 0 (ERG1 Potassium Channel)
RN  - 0 (Ether-A-Go-Go Potassium Channels)
RN  - 0 (KCNH2 protein, human)
RN  - 0 (Shaker Superfamily of Potassium Channels)
RN  - 04Y7590D77 (Isoleucine)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - ERG1 Potassium Channel
MH  - Ether-A-Go-Go Potassium Channels/chemistry/drug effects/genetics/*metabolism
MH  - Humans
MH  - Hydrophobic and Hydrophilic Interactions
MH  - *Ion Channel Gating/drug effects
MH  - Isoleucine
MH  - Membrane Potentials
MH  - Models, Molecular
MH  - Molecular Sequence Data
MH  - Mutagenesis, Site-Directed
MH  - Mutation
MH  - Protein Conformation
MH  - Protein Structure, Tertiary
MH  - Shaker Superfamily of Potassium Channels/chemistry/metabolism
MH  - Structure-Activity Relationship
MH  - Xenopus laevis
OTO - NOTNLM
OT  - channel gating
OT  - hERG
OT  - potassium channels
EDAT- 2013/06/14 06:00
MHDA- 2013/10/25 06:00
CRDT- 2013/06/14 06:00
PHST- 2013/06/14 06:00 [entrez]
PHST- 2013/06/14 06:00 [pubmed]
PHST- 2013/10/25 06:00 [medline]
AID - ajpcell.00147.2013 [pii]
AID - 10.1152/ajpcell.00147.2013 [doi]
PST - ppublish
SO  - Am J Physiol Cell Physiol. 2013 Aug 15;305(4):C468-78. doi: 
      10.1152/ajpcell.00147.2013. Epub 2013 Jun 12.