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Assembly of plant Shaker-like K-out channels requires two distinct sites of the channel alpha-subunit

  • SKOR and GORK are outward-rectifying plant potassium channels from Arabidopsis thaliana. They belong to the Shaker superfamily of voltage-dependent K+ channels. Channels of this class are composed of four alpha-subunits and subunit assembly is a prerequisite for channel function. In this study the assembly mechanism of SKOR was investigated using the yeast two-hybrid system and functional assays in Xenopus oocytes and in yeast. We demonstrate that SKOR and GORK physically interact and assemble into heteromeric K-out channels. Deletion mutants and chimeric proteins generated from SKOR and the K-in channel alpha-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains thatchannel a-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains that are crucial for channel assembly were identified: i), a proximal interacting region comprising a putative cyclic nucleotide-binding domain together with 33 amino acids just upstream of this domain, and ii),SKOR and GORK are outward-rectifying plant potassium channels from Arabidopsis thaliana. They belong to the Shaker superfamily of voltage-dependent K+ channels. Channels of this class are composed of four alpha-subunits and subunit assembly is a prerequisite for channel function. In this study the assembly mechanism of SKOR was investigated using the yeast two-hybrid system and functional assays in Xenopus oocytes and in yeast. We demonstrate that SKOR and GORK physically interact and assemble into heteromeric K-out channels. Deletion mutants and chimeric proteins generated from SKOR and the K-in channel alpha-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains thatchannel a-subunit KAT1 revealed that the cytoplasmic C-terminus of SKOR determines channel assembly. Two domains that are crucial for channel assembly were identified: i), a proximal interacting region comprising a putative cyclic nucleotide-binding domain together with 33 amino acids just upstream of this domain, and ii), a distal interacting region showing some resemblance to the K-T domain of KAT1. Both regions contributed differently to channel assembly. Whereas the proximal interacting region was found to be active on its own, the distal interacting region required an intact proximal interacting region to be active. K-out alpha-subunits did not assemble with K-in alpha-subunits because of the absence of interaction between their assembly sitesshow moreshow less

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Metadaten
Author:Ingo DreyerORCiDGND, Fabien Poree, A. Schneider, J. Mittelstadt, Adam Bertl, H. Sentenac, Jean-Baptiste Thibaud, Bernd Müller-RöberORCiDGND
ISSN:0006-3495
Document Type:Article
Language:English
Year of first Publication:2004
Year of Completion:2004
Release Date:2017/03/24
Source:Biophysical Journal. - ISSN 0006-3495. - 87 (2004), 2, S. 858 - 872
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Biochemie und Biologie
Peer Review:Referiert