Disease-associated mutations in the fourth cytoplasmic loop of cystic fibrosis transmembrane conductance regulator compromise biosynthetic processing and chloride channel activity

Fabian S. Seibert, Paul Linsdell, Tip W. Loo, John W. Hanrahan, David M. Clarke, John R. Riordan

Résultat de recherche: Articleexamen par les pairs

114 Citations (Scopus)

Résumé

A cluster of 18 point mutations in exon 17b of the cystic fibrosis transmembrane conductance regulator (CFTR) gene has been detected in patients with cystic fibrosis. These mutations cause single amino acid substitutions in the most C-terminal cytoplasmic loop (CL4, residues 1035-1102) of the CFTR chloride channel. Heterologous expression of the mutants showed that 12 produced only core-glycosylated CFTR, which was retained in the endoplasmic reticulum; the other six mutants matured and reached the cell surface. In some cases substitution of one member of pairs of adjacent residues resulted in misprocessing, whereas the other did not. Thus, the secondary structure of CL4 may contribute crucially to the proper folding of the entire CFTR molecule. Cyclic AMP-stimulated iodide efflux was not detected from cells expressing the misprocessed variants but was from the other six, indicating that their mutations cause relatively subtle channel defects. Consistent with this, these latter mutations generally are present in patients who are pancreatic-sufficient, while the processing mutants are mostly from patients who are pancreatic-insufficient. Single-channel patch-clamp analysis demonstrated that the processed mutants had the same ohmic conductance as wild-type CFTR, but a lower open probability, generally due to an increase in channel mean closed time and a reduction in mean open time. This suggests that mutations in CL4 do not affect pore properties of CFTR, but disrupt the mechanism of channel gating.

Langue d'origineEnglish
Pages (de-à)15139-15145
Nombre de pages7
JournalJournal of Biological Chemistry
Volume271
Numéro de publication25
DOI
Statut de publicationPublished - 1996
Publié à l'externeOui

Note bibliographique

Funding Information:
We gratefully acknowledge financial support from the Russian Government, Ministry of Education (research was made possible due to funds provided aiming at maximizing ITMO University's competitive advantage among world's leading educational centres) and centre for joint use of scientific equipment "The upper Volga region centre of physico-chemical research".

ASJC Scopus Subject Areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Empreinte numérique

Plonger dans les sujets de recherche 'Disease-associated mutations in the fourth cytoplasmic loop of cystic fibrosis transmembrane conductance regulator compromise biosynthetic processing and chloride channel activity'. Ensemble, ils forment une empreinte numérique unique.

Citer