Fast degradation of the auxiliary subunit of Na+/K+-ATPase in the plasma membrane of HeLa cells
- 1 July 2008
- journal article
- Published by The Company of Biologists in Journal of Cell Science
- Vol. 121 (13), 2159-2168
- https://doi.org/10.1242/jcs.022905
Abstract
The cell-surface expression and function of multisubunit plasma membrane proteins are regulated via interactions between catalytic subunits and auxiliary subunits. Subunit assembly in the endoplasmic reticulum is required for the cell-surface expression of the enzyme, but little is known about subunit interactions once it reaches the plasma membrane. Here we performed highly quantitative analyses of the catalytic (α1) and auxiliary (β1 and β3) subunits of Na+/K+-ATPase in the HeLa cell plasma membrane using isoform-specific antibodies and a cell-surface protein labeling procedure. Our results indicate that although the β-subunit is required for the cell-surface expression of the α-subunit, the plasma membrane contains more α-subunits than β-subunits. Pulse-labeling and chasing of the cell-surface proteins revealed that degradation of the β-subunits was much faster than that of the α1-subunit. Ubiquitylation, as well as endocytosis, was involved in the fast degradation of the β1-subunit. Double knockdown of the β1- and β3-subunits by RNAi resulted in the disappearance of these β-subunits but not the α1-subunit in the plasma membrane. All these results indicate that the α- and β-subunits of Na+/K+-ATPase are assembled in the endoplasmic reticulum, but are disassembled in the plasma membrane and undergo different degradation processes.Keywords
This publication has 55 references indexed in Scilit:
- Src-mediated Inter-receptor Cross-talk between the Na+/K+-ATPase and the Epidermal Growth Factor Receptor Relays the Signal from Ouabain to Mitogen-activated Protein KinasesPublished by Elsevier BV ,2002
- Phylogenetic analysis of the cadherin superfamily allows identification of six major subfamilies besides several solitary membersJournal of Molecular Biology, 2000
- Tenascin-R Is a Functional Modulator of Sodium Channel β SubunitsPublished by Elsevier BV ,1999
- Degradation of Connexin43 Gap Junctions Involves both the Proteasome and the LysosomeExperimental Cell Research, 1997
- Inactivation properties of voltage-gated K+ channels altered by presence of β-subunitNature, 1994
- Primary structure of avian H+/K+-ATPase β-subunitBiochimica et Biophysica Acta (BBA) - Biomembranes, 1994
- The functional role of the β‐subunit in the maturation and intracellular transport of Na,K‐ATPaseFEBS Letters, 1991
- Isozymes of the Na+/K+-ATPaseBiochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1989
- Structural basis for E1–E2 conformational transitions in Na, K-pump and Ca-pump proteinsThe Journal of Membrane Biology, 1988
- The influence of some cations on an adenosine triphosphatase from peripheral nervesBiochimica et Biophysica Acta, 1957