Referenced in: none

Automatically associated channels: ClC1 , ClC4

Title: Functional and structural conservation of CBS domains from CLC chloride channels.

Authors: Raúl Estévez, Michael Pusch, Carles Ferrer-Costa, Modesto Orozco, Thomas J Jentsch

Journal, date & volume: J. Physiol. (Lond.), 2004 Jun 1 , 557, 363-78

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/14724190

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.