Novel isoforms of the beta and gamma subunits of the Xenopus epithelial Na channel provide information about the amiloride binding site and extracellular sodium sensing
Détails
ID Serval
serval:BIB_7B085FE84684
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Novel isoforms of the beta and gamma subunits of the Xenopus epithelial Na channel provide information about the amiloride binding site and extracellular sodium sensing
Périodique
Proceedings of the National Academy of Sciences of the United States of America
ISSN
0027-8424 (Print)
Statut éditorial
Publié
Date de publication
05/1997
Volume
94
Numéro
11
Pages
5949-54
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: May 27
Research Support, Non-U.S. Gov't --- Old month value: May 27
Résumé
We have previously identified three homologous subunits alpha, beta, and gamma of the highly selective amiloride-sensitive Na channel from the Xenopus laevis kidney A6 cell line, which forms a tight epithelium in culture. We report here two novel genes, termed beta2 and gamma2, which share 90 and 92% sequence identity with the previously characterized beta and gamma XENaC, respectively. beta2 and gamma2 transcripts were detected in lung, kidney, and A6 cells grown on porous substrate. The physiological and pharmacological profile of the Na channel expressed after alphabeta2gamma XENaC cRNA injection in Xenopus oocyte did not differ from alphabetagamma XENaC. By contrast, the channel expressed after alphabetagamma2 injection showed: (i) a lower maximal amiloride-sensitive sodium current, (ii) a higher apparent affinity for external sodium and inactivation of the sodium current by high sodium concentrations, and (iii) a lower apparent affinity for amiloride (KI alphabetagamma2; 1.34 microM versus alphabetagamma 0.35 microM). These data indicate that the gamma (and/or gamma2) subunit participates in amiloride binding and the sensing of the extracellular sodium concentration. The close homology between gamma and gamma2 will help to define the domains involved in sensing external sodium and in the structure of this important drug receptor.
Mots-clé
Amiloride/metabolism/pharmacology
Amino Acid Sequence
Animals
Binding Sites
Cell Line
DNA Primers
Epithelium/physiology
Kidney/*physiology
Kinetics
Lung/physiology
Macromolecular Substances
Molecular Sequence Data
Oocytes/physiology
Organ Specificity
Polymerase Chain Reaction
RNA, Complementary
Recombinant Fusion Proteins/biosynthesis/chemistry
Sodium/*metabolism
Sodium Channels/biosynthesis/*chemistry/*physiology
Xenopus laevis
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 13:38
Dernière modification de la notice
20/08/2019 15:36