Structure and function of the ion channel ICIn

Normal function of organs and cells is tightly linked to the cytoarchitecture. Control of the cell volume is therefore vital for the organism. A widely established strategy of cells to counteract swelling is the activation of chloride and potassium channels, which leads to a net efflux of salt followed by water - a process termed regulatory volume decrease. Since there is evidence for swelling-dependent chloride channels (ICIswell) being activated also during pathological processes, the identification of the molecular entity underlying ICIwell is of utmost importance. Several proteins are discussed as the channel forming ICIwell, i.e. phospholemman, p-glycoprotein, CLC-3 and ICIn. In this review we would like to focus on the properties of ICIn, a protein cloned from a (M) under bar adin (D) under bar arby (c) under bar anine (k) under bar idney (MDCK) cell library whose expression in Xenopus laevis oocytes resulted in a nucleotide sensitive, outwardly rectifying chloride current closely resembling the biophysical properties of ICIswell. Copyright (C) 2000 S. Karger AG, Basel.