The second half of the cystic fibrosis transmembrane conductance regulator forms a functional chloride channel

Sreenivas Devidas, Hongwen Yue, William B. Guggino

Research output: Contribution to journalArticle

Abstract

The cystic fibrosis transmembrane conductance regulator (CFTR) consists of two transmembrane domains (TMDs), TMD1 and TMD2, two cytoplasmic nucleotide binding domains (NBDs), NBD1 and NBD2, and a regulatory domain. To elucidate the complex function of the CFTR, deletion constructs encompassing the second half of the CFTR distal to the first transmembrane domain were expressed in Xenopus oocytes and IB3 cells (a cystic fibrosis cell line). Constructs containing the regulatory domain, the second transmembrane domain, and the second nucleotide binding domain formed constitutively active channels, which were further stimulated upon the addition of cAMP. On the other hand, a construct encompassing the second transmembrane domain and the second nucleotide binding domain was stimulated to a small but noticeable extent upon the addition of cAMP. The selectivity of the second-half construct was the same for iodide and chloride, in contrast to the selectivity of wild-type CFTR, which is Cl- > I-. However, both constructs displayed single-channel conductances that were significantly smaller than those displayed by the first half of the CFTR. We conclude that regions of the second transmembrane domain may contribute to the overall channel of the pore, although the first half of the CFTR may confer its selectivity.

Original languageEnglish (US)
Pages (from-to)29373-29380
Number of pages8
JournalJournal of Biological Chemistry
Volume273
Issue number45
DOIs
StatePublished - Nov 6 1998

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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