Processing, intracellular transport, and functional expression of endogenous and exogenous alpha-beta 3 Na,K-ATPase complexes in Xenopus oocytes.

Détails

ID Serval
serval:BIB_7302E26390AE
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Processing, intracellular transport, and functional expression of endogenous and exogenous alpha-beta 3 Na,K-ATPase complexes in Xenopus oocytes.
Périodique
Journal of Biological Chemistry
Auteur(s)
Jaunin P., Horisberger J.D., Richter K., Good P.J., Rossier B.C., Geering K.
ISSN
0021-9258
Statut éditorial
Publié
Date de publication
01/1992
Peer-reviewed
Oui
Volume
267
Numéro
1
Pages
577-585
Langue
anglais
Résumé
The minimal functional Na,K-ATPase unit is composed of a catalytic alpha-subunit and a glycosylated beta-subunit. So far three putative beta-isoforms have been described, but only beta 1-isoforms have been identified clearly as part of a purified active enzyme complex. In this study we provide evidence that a putative beta 3-isoform might be the functional component of Xenopus oocyte Na,K-ATPase. beta 3-isoforms are expressed in the oocyte plasma membrane together with alpha-subunits, but beta 3-isoforms are synthesized to a lesser extent than alpha-subunits. The unassembled oocyte alpha-subunits accumulate in an immature trypsin-sensitive form most likely in the endoplasmic reticulum (ER). Injection of both beta 1- and beta 3-cRNA into oocytes abolishes the transport constraint of the oocyte alpha-subunit, renders it trypsin-resistant, and finally leads to an increased number of functional pumps at the plasma membrane. In addition, beta 3-isoforms as beta 1-isoforms depend on the concomitant synthesis of alpha-subunits to be able to leave the ER and to become fully glycosylated. Finally, alpha-beta 1 and alpha-beta 3 complexes expressed at the plasma membrane appear to have similar transport properties as assessed by ouabain binding, rubidium uptake, and electrophysiological measurements in oocytes coexpressing exogenous alpha 1- and beta 1- or beta 3-isoforms. Thus our data indicate that beta 3-isoforms have functional qualities similar to beta 1-isoforms. They can assemble and impose a structural reorganization to newly synthesized alpha-subunits which permits the exit from the ER and the expression of functional Na,K-pumps at the plasma membrane.
Mots-clé
Animals, Biological Transport, Cell Fractionation, Electrophoresis, Polyacrylamide Gel, Endoplasmic Reticulum/enzymology, Female, Glycosylation, Hydrolysis, Isoenzymes/biosynthesis, Isoenzymes/metabolism, Ovum/enzymology, Precipitin Tests, Protein Processing, Post-Translational, Sodium-Potassium-Exchanging ATPase/biosynthesis, Sodium-Potassium-Exchanging ATPase/metabolism, Trypsin/chemistry, Xenopus
Pubmed
Web of science
Création de la notice
24/01/2008 13:28
Dernière modification de la notice
03/03/2018 18:18
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