Molecular cloning and expression of a chloride ion channel of cell nuclei

Ion channels are known to be present on the plasma membrane of virtually all cells and have been found on the membranes of various intracellular organelles. However, until recently they were believed not to occur at the nuclear membrane. In this study we describe the molecular cloning and characterization of a nuclear ion channel protein, designated nuclear chloride channel-27 (NCC27), from the human myelomonocytic cell line, U937. NCC27 is a novel chloride ion channel protein that was found to localize principally to the cell nucleus. Its only known homologue is a bovine chloride ion channel protein (p64) believed to localize to internal organelles. NCC27 therefore represents the first human member of a new class of organellar chloride ion channel proteins.