PT  - JOURNAL ARTICLE
AU  - Lorena Varela
AU  - Alex C. Hendry
AU  - Diego Cantoni
AU  - Jose L. Ortega-Roldan
TI  - The membrane insertion of soluble CLIC1 into active chloride channels is triggered by specific divalent cations
AID  - 10.1101/638080
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 638080
4099  - http://biorxiv.org/content/early/2019/05/14/638080.short
4100  - http://biorxiv.org/content/early/2019/05/14/638080.full
AB  - The CLIC family display the unique feature of altering its structure from a soluble form to a membrane-bound chloride channel. CLIC1, a member of this family, can be found in the cytoplasm or in nuclear, ER and plasma membranes, with membrane overexpression linked to tumour proliferation. The molecular switch promoting CLIC1 membrane insertion has been related to environmental factors, but it still remains unclear. Here, we use solution NMR studies to confirm that both the soluble and membrane bound forms are in the same oxidation state. Our data from fluorescence assays and chloride efflux assays indicate that Ca2+ and Zn2+ trigger association to the membrane into active chloride channels. We use fluorescence microscopy to confirm that an increase of the intracellular Ca2+ leads to re-localisation of CLIC1 to both plasma and internal membranes. Thus, our results allow the identification of Ca2+ and Zn2+ as the molecular switch promoting CLIC1 membrane insertion into active chloride channels.