A role for the beta-subunit in the expression of functional Na+-K+-ATPase in Xenopus oocytes
Details
Serval ID
serval:BIB_54807FE286F8
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
A role for the beta-subunit in the expression of functional Na+-K+-ATPase in Xenopus oocytes
Journal
American Journal of Physiology
ISSN
0363-6143
Publication state
Published
Issued date
11/1989
Volume
257
Number
5 Pt 1
Pages
C851-8
Notes
Journal Article
Research Support, Non-U.S. Gov't --- Old month value: Nov
Research Support, Non-U.S. Gov't --- Old month value: Nov
Abstract
In all cellular systems studied so far, the catalytic alpha- and the glycosylated beta-subunit of Na+-K+-ATPase are coordinately synthesized and are assembled into stoichiometric alpha, beta-complexes. In contrast to these data, in this study we show that the fully grown oocyte of Xenopus laevis synthesizes much less beta-subunit than alpha-subunit. The alpha-subunit produced in excess over the beta-subunit is membrane associated but highly trypsin sensitive and can be compared with the immature alpha-subunit population identified in epithelial cells immediately after synthesis (K. Geering, J. P. Kraehenbuhl, and B.C. Rossier, J. Cell Biol. 105: 2613-2619, 1987). The Xenopus oocyte thus turns out to be a unique system to study the functional role of the beta-subunit. Injection of beta-subunit-specific mRNA transcribed in vitro from a beta-cDNA clone (derived from Xenopus kidney, A6 cells) into oocytes results in translation of a glycosylated beta-subunit. The synthesis of this exogenous beta-subunit increases significantly the proportion of trypsin-resistant oocyte alpha-subunits able to perform cation-dependent conformational changes. In addition, 25-65% more ouabian binding sites are expressed at the plasma membrane in beta-mRNA-injected oocytes. In contrast, newly synthesized alpha-subunit translated after injection of size-fractionated mRNA enriched in alpha-mRNA remains trypsin sensitive as the oocyte alpha-subunit. These data suggest that association of the beta-subunit to the alpha-subunit provokes a structural rearrangement of the alpha-subunit that might be a first step toward the functional maturation of the Na+-K+-ATPase and its expression at the plasma membrane.
Keywords
Animals
Cell Membrane/enzymology
Drug Resistance
Female
Na(+)-K(+)-Exchanging ATPase/biosynthesis/*physiology
Oocytes/enzymology/*physiology
RNA, Messenger/genetics/pharmacology
Transcription, Genetic
Trypsin/pharmacology
Xenopus/*physiology
Pubmed
Web of science
Create date
24/01/2008 12:28
Last modification date
20/08/2019 14:09