Role of the transmembrane and extracytoplasmic domain of beta subunits in subunit assembly, intracellular transport, and functional expression of Na,K-pumps

Détails

ID Serval
serval:BIB_EE9F0801F9FD
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Role of the transmembrane and extracytoplasmic domain of beta subunits in subunit assembly, intracellular transport, and functional expression of Na,K-pumps
Périodique
Journal of Cell Biology
Auteur(s)
Jaunin  P., Jaisser  F., Beggah  A. T., Takeyasu  K., Mangeat  P., Rossier  B. C., Horisberger  J. D., Geering  K.
ISSN
0021-9525 (Print)
Statut éditorial
Publié
Date de publication
12/1993
Volume
123
Numéro
6 Pt 2
Pages
1751-9
Notes
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S. --- Old month value: Dec
Résumé
The ubiquitous Na,K- and the gastric H,K-pumps are heterodimeric plasma membrane proteins composed of an alpha and a beta subunit. The H,K-ATPase beta subunit (beta HK) can partially act as a surrogate for the Na,K-ATPase beta subunit (beta NK) in the formation of functional Na,K-pumps (Horisberger et al., 1991. J. Biol. Chem. 257:10338-10343). We have examined the role of the transmembrane and/or the ectodomain of beta NK in (a) its ER retention in the absence of concomitant synthesis of Na,K-ATPase alpha subunits (alpha NK) and (b) the functional expression of Na,K-pumps at the cell surface and their activation by external K+. We have constructed chimeric proteins between Xenopus beta NK and rabbit beta HK by exchanging their NH2-terminal plus transmembrane domain with their COOH-terminal ectodomain (beta NK/HK, beta HK/NK). We have expressed these constructs with or without coexpression of alpha NK in the Xenopus oocyte. In the absence of alpha NK, Xenopus beta NK and all chimera that contained the ectodomain of beta NK were retained in the ER while beta HK and all chimera with the ectodomain of beta HK could leave the ER suggesting that ER retention of unassembled Xenopus beta NK is mediated by a retention signal in the ectodomain. When coexpressed with alpha NK, only beta NK and beta NK/HK chimera assembled efficiently with alpha NK leading to similar high expression of functional Na,K-pumps at the cell surface that exhibited, however, a different apparent K+ affinity. beta HK or chimera with the transmembrane domain of beta HK assembled less efficiently with alpha NK leading to lower expression of functional Na,K-pumps with a different apparent K+ affinity. The data indicate that the transmembrane domain of beta NK is important for efficient assembly with alpha NK and that both the transmembrane and the ectodomain of beta subunits play a role in modulating the transport activity of Na,K-pumps.
Mots-clé
Amino Acid Sequence Animals Base Sequence Cell Membrane/*enzymology Female Gastric Mucosa/enzymology *Gene Expression H(+)-K(+)-Exchanging ATPase/*biosynthesis/metabolism Macromolecular Substances Molecular Sequence Data Na(+)-K(+)-Exchanging ATPase/*biosynthesis/metabolism Oocytes/physiology Polymerase Chain Reaction *Protein Biosynthesis *Protein Processing, Post-Translational Rabbits Recombinant Fusion Proteins/biosynthesis/metabolism Xenopus laevis
Pubmed
Web of science
Open Access
Oui
Création de la notice
24/01/2008 13:28
Dernière modification de la notice
09/05/2019 3:09
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