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Research Papers
Potassium Channel Gating in the Absence of the Highly Conserved Glycine of the Inner Transmembrane Helix
Avia Rosenhouse-Dantsker and Diomedes E. Logothetis
volume 1 | issue 3
May/June 2007Pages: 189 - 197
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Potassium channel activation regulates cellular excitability, such as in neuronal and cardiac cells. Regulation of ion channel activity relies on a switching mechanism between two major conformations, the open and closed states, known as gating. It has been suggested that potassium channels are generally gated via a pivoted mechanism of the pore-lining helix (TM2) in the proximity of a glycine that is conserved in about 80% of potassium channels, even though about 20% of the channels lack a glycine at this position. Yet, as we show in G-protein gated potassium (Kir3) channels that lack a glycine at this position, the βγ subunits of G-proteins can still stimulate channel activity. Our results suggest that the effect of mutation of the central glycine (at position 175 in Kir3.4) on βγ-induced whole-cell currents is related to the extent of the interaction between residues located at the position of the central glycine and two residues, one located in the signature sequence of the selectivity filter (T149 in Kir3.4) and the other in the pore helix (E147 in Kir3.4). Our results also suggest that interactions with position 149 are more detrimental to channel function than interactions with position 147. The ability of Gβγ to overcome such restraining interactions is likely to depend on a combination of characteristics specific to each residue.
Authors
Avia Rosenhouse-Dantsker
Mount Sinai School of Medicine, New York, NY
Diomedes E. Logothetis
Mount Sinai School of Medicine, New York, NY
We now provide open access to journal articles published online for one year or more. This article may be downloaded at the following link:
Download PDF If the document does not open, please right-click on the link (control-click on a Macintosh) and select the option to save the file to disk.