Role of beta-subunit domains in the assembly, stable expression, intracellular routing, and functional properties of Na,K-ATPase

Détails

ID Serval
serval:BIB_400D160593A6
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Role of beta-subunit domains in the assembly, stable expression, intracellular routing, and functional properties of Na,K-ATPase
Périodique
Journal of Biological Chemistry
Auteur(s)
Hasler  U., Wang  X., Crambert  G., Beguin  P., Jaisser  F., Horisberger  J. D., Geering  K.
ISSN
0021-9258 (Print)
Statut éditorial
Publié
Date de publication
11/1998
Volume
273
Numéro
46
Pages
30826-35
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Nov 13
Résumé
The beta-subunit of Na,K-ATPase (betaNK) interacts with the catalytic alpha-subunit (alphaNK) in the ectodomain, the transmembrane, and the cytoplasmic domain. The functional significance of these different interactions was studied by expressing alphaNK in Xenopus oocytes along with N-terminally modified betaNK or with chimeric betaNK/betaH,K-ATPase (betaHK). Complete truncation of the betaNK N terminus allows for cell surface-expressed, functional Na,K-pumps that exhibit, however, reduced apparent K+ and Na+ affinities as assessed by electrophysiological measurements. A mutational analysis suggests that these functional effects are not related to a direct interaction of the beta N terminus with the alphaNK but rather that N-terminal truncation induces a conformational change in another functionally relevant beta domain. Comparison of the functional properties of alphaNK.betaNK, alphaNK.betaHK, or alphaNK. betaNK/betaHK complexes shows that the effect of the betaNK on K+ binding is mainly mediated by its ectodomain. Finally, betaHK/NK containing the transmembrane domain of betaHK produces stable but endoplasmic reticulum-retained alphaNK.beta complexes, while alphaNK/betaHK complexes can leave the ER but exhibit reduced ouabain binding capacity and transport function. Thus, interactions of both the transmembrane and the ectodomain of betaNK with alphaNK are necessary to form correctly folded Na,K-ATPase complexes that can be targeted to the plasma membrane and/or become functionally competent. Furthermore, the beta N terminus plays a role in the beta-subunit's folding necessary for correct interactions with the alpha-subunit.
Mots-clé
Amino Acid Sequence Animals Catalytic Domain Cytoplasm/enzymology Molecular Sequence Data Mutagenesis, Site-Directed Na(+)-K(+)-Exchanging ATPase/genetics/*metabolism Point Mutation Potassium/metabolism Protein Conformation Sodium/metabolism Structure-Activity Relationship Xenopus
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 13:28
Dernière modification de la notice
20/08/2019 14:37
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