Chloride channel and chloride conductance regulator domains of CFTR, the cystic fibrosis transmembrane conductance regulator

Erik M. Schwiebert, Marcelo M. Morales, Sreenivas Devidas, Marie E. Egan, William B. Guggino

Research output: Contribution to journalArticle

Abstract

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 CFYRs 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, 36Clefflux 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 α-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.

Original languageEnglish (US)
Pages (from-to)2674-2679
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume95
Issue number5
DOIs
StatePublished - Mar 3 1998

ASJC Scopus subject areas

  • General

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