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. 1998 Mar 1;330(Pt 2):1015–1021. doi: 10.1042/bj3301015

Evidence for the intracellular location of chloride channel (ClC)-type proteins: co-localization of ClC-6a and ClC-6c with the sarco/endoplasmic-reticulum Ca2+ pump SERCA2b.

G Buyse 1, D Trouet 1, T Voets 1, L Missiaen 1, G Droogmans 1, B Nilius 1, J Eggermont 1
PMCID: PMC1219239  PMID: 9480924

Abstract

Chloride channel protein (ClC)-6a and ClC-6c, a kidney-specific splice variant with a truncated C-terminus, are proteins that belong structurally to the family of voltage-dependent chloride channels. Attempts to characterize functionally ClC-6a or ClC-6c in Xenopus oocytes have so far been negative. Similarly, expression of both ClC-6 isoforms in mammalian cells failed to provide functional information. One possible explanation of these negative results is that ClC-6 is an intracellular chloride channel rather than being located in the plasma membrane. We therefore studied the subcellular location of ClC-6 isoforms by transiently transfecting COS and CHO cells with epitope-tagged versions of ClC-6a and ClC-6c. Confocal imaging of transfected cells revealed for both ClC-6 isoforms an intracellular distribution pattern that clearly differed from the peripheral location of CD2, a plasma-membrane glycoprotein. Furthermore, dual-labelling experiments of COS cells co-transfected with ClC-6a or -6c and the sarco/endoplasmic-reticulum Ca2+ pump (SERCA2b) indicated that the ClC-6 isoforms co-localized with the SERCA2b Ca2+ pump. Thus ClC-6a and ClC-6c are intracellular membrane proteins, most likely residing in the endoplasmic reticulum. In view of their structural similarity to proven chloride channels, ClC-6 isoforms are molecular candidates for intracellular chloride channels.

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Selected References

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