期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：5
页码：2674-2679
DOI：10.1073/pnas.95.5.2674
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：CFTR is a cyclic AMP (cAMP)-activated chloride (Cl-) channel and a regulator of outwardly rectifying Cl- channels (ORCCs) in airway epithelia. CFTR regulates ORCCs by facilitating the release of ATP out of cells. Once released from cells, ATP stimulates ORCCs by means of a purinergic receptor. To define the domains of CFTR important for Cl- channel function and/or ORCC regulator function, mutant CFTRs with N- and C-terminal truncations and selected individual amino acid substitutions were created and studied by transfection into a line of human airway epithelial cells from a cystic fibrosis patient (IB3-1) or by injection of in vitro transcribed complementary RNAs (cRNAs) into Xenopus oocytes. Two-electrode voltage clamp recordings, 36Cl- efflux assays, and whole cell patch-clamp recordings were used to assay for the Cl- channel function of CFTR and for its ability to regulate ORCCs. The data showed that the first transmembrane domain (TMD-1) of CFTR, especially predicted -helices 5 and 6, forms an essential part of the Cl- channel pore, whereas the first nucleotide-binding and regulatory domains (NBD1/R domain) are essential for its ability to regulate ORCCs. Finally, the data show that the ability of CFTR to function as a Cl- channel and a conductance regulator are not mutually exclusive; one function could be eliminated while the other was preserved.
