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Research Papers
Structural Diversity in the Cytoplasmic Region of G Protein-Gated Inward Rectifier K+ Channels
Atsushi Inanobe, Takanori Matsuura, Atsushi Nakagawa and Yoshihisa Kurachi
volume 1 | issue 1
January/February 2007This is an open-access article
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Inward rectifier K+ (Kir) channels can be functionally categorized into two groups: those that are constitutively active and those that are constitutively inactive, with examples such as Kir2.x and Kir3.x, respectively. Their cytoplasmic regions are thought to be critical for control of channel gating, but a structural basis for this hypothesis is not known. In this study, we report a structure for the cytoplasmic region of a G protein-gated Kir channel, Kir3.2, and compare it with those of Kir3.1 and Kir2.1 channels. The isolated cytoplasmic region of Kir3.2 forms a tetrameric assembly in solution and also in the crystal. While the secondary structure arrangement and the subunit interface of the Kir3.2 crystal structure are found to be nearly identical to those of Kir3.1 and Kir2.1, it is quite different at and around loops between βC- and βD-strands and between βH- and βI-strands. These structural elements are located at the interface with the plasma membrane. Therefore, these structural elements could associate with the Kir channel transmembrane helices and be involved in the regulation of Kir channel gating.
Authors
Atsushi Inanobe
Osaka University Graduate School of Medicine
Takanori Matsuura
Osaka University, Institute of Protein Research
Atsushi Nakagawa
Osaka University, Institute of Protein Research
Yoshihisa Kurachi
Osaka University Graduate School of Medicine
This is an open-access article
Download PDFIf 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.