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Role of the Na,K-ATPase beta-subunit in the cellular accumulation and maturation of the enzyme as assessed by glycosylation inhibitors.
Journal article

Role of the Na,K-ATPase beta-subunit in the cellular accumulation and maturation of the enzyme as assessed by glycosylation inhibitors.

  • 1988-08-01
Published in:
  • The Journal of membrane biology. - 1988
1-Deoxynojirimycin
Alkaloids
Animals
Cell Line
Glucosamine
Glycoproteins
Glycosylation
Precipitin Tests
Protein Conformation
Protein Processing, Post-Translational
Sodium-Potassium-Exchanging ATPase
Swainsonine
Trypsin
Tunicamycin
English No functional role could yet be established for the glycosylated beta-subunit of the Na,K-ATPase. In this study, we describe the intracellular processing of the beta-subunit as a glycoprotein in toad bladder cells and the consequences of its structural perturbation with glycosylation inhibitors on the cellular expression of the alpha- and beta-subunits and on the structural and functional maturation of the enzyme. Controlled trypsinolysis of homogenates from pulse-labeled cells reveals that the beta-subunit is subjected to glycosylation-dependent structural rearrangements during its intracellular routing. Inhibition of correct terminal glycosylation of the beta-subunit with deoxynojirimycin or swainsonine has no effect on the trypsin sensitivity of the alpha-subunit, its ability to perform cation-dependent conformation changes or the cellular Na,K-ATPase activity. Acquisition of core-sugars is sufficient for the enzyme to assume its catalytic functions. On the other hand, complete inhibition of glycosylation with tunicamycin leads to a destabilization of both the beta- and the alpha-subunits as judged by their higher trypsin sensitivity. In addition, tunicamycin treatment results in a decrease of the amount of newly synthesized beta- and alpha-subunit indicating that a glycoprotein, possibly the beta-subunit itself, plays a role in the efficient accumulation of the alpha-subunit in the endoplasmic reticulum.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://folia.unifr.ch/global/documents/137070
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