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Functional and structural conservation of CBS domains from CLC chloride channels

Item Type:Article
Title:Functional and structural conservation of CBS domains from CLC chloride channels
Creators Name:Estevez, R. and Pusch, M. and Ferrer-Costa, C. and Orozco, M. and Jentsch, T.J.
Abstract:All eukaryotic CLC Cl(-) channel subunits possess a long cytoplasmic carboxy-terminus that contains two so-called CBS (cystathionine beta-synthase) domains. These domains are found in various unrelated proteins from all phylae. The crystal structure of the CBS domains of inosine monophosphate dehydrogenase (IMPDH) is known, but it is not known whether this structure is conserved in CLC channels. Working primarily with ClC-1, we used deletion scanning mutagenesis, coimmunoprecipitation and electrophysiology to demonstrate that its CBS domains interact. The replacement of CBS domains of ClC-1 with the corresponding CBS domains from other CLC channels and even human IMPDH yielded functional channels, indicating a high degree of structural conservation. Based on a homology model of the pair of CBS domains of CLC channels, we identified some residues that, when mutated, affected the common gate which acts on both pores of the dimeric channel. Thus, we propose that the structure of CBS domains from CLC channels is highly conserved and that they play a functional role in the common gate.
Keywords:Amino Acid Sequence, Cultured Cells, Chloride Channels, Cystathionine beta-Synthase, Dimerization, Immunoprecipitation, Ion Channel Gating, Molecular Models, Molecular Sequence Data, Mutation, Oocytes, Patch-Clamp Techniques, Tertiary Protein Structure, Sequence Alignment, Animals, Xenopus
Source:Journal of Physiology
Publisher:Blackwell Publishing
Number:Pt 2
Page Range:363-378
Date:1 June 2004
Official Publication:https://doi.org/10.1113/jphysiol.2003.058453
PubMed:View item in PubMed

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