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PMID: 9477575 Published · ppublish English Journal Article Research Support, U.S. Gov't, Non-P.H.S.

The molecular chaperone calnexin associates with the vacuolar H(+)-ATPase from oat seedlings.

The Plant cell ·Vol. 10 ·No. 1 ·1998-01-00 ·Pages 119-30

Li X, Su RT, Hsu HT, Sze H

Abstract

Acidification of endomembrane compartments by the vacuolar-type H(+)-ATPase (V-ATPase) is central to many cellular processes in eukaryotes, including osmoregulation and protein sorting. The V-ATPase complex consists of a peripheral sector (V1) and a membrane integral sector (V0); however, it is unclear how the multimeric enzyme is assembled. A 64-kD polypeptide that had copurified with oat V-ATPase subunits has been identified as calnexin, an integral protein on the endoplasmic reticulum. To determine whether calnexin interacted physically with the V-ATPase, microsomal membranes were Triton X-100 solubilized, and the protein-protein interaction was analyzed by coimmunoprecipitation. Monoclonal antibodies against calnexin precipitated both calnexin and V-ATPase subunits, including A and B and those of 44, 42, 36, 16, and 13 kD. A monoclonal antibody against subunit A precipitated the entire V-ATPase complex as well as calnexin and BiP, an endoplasmic reticulum lumen chaperone. The results support our hypothesis that both calnexin and BiP act as molecular chaperones in the folding and assembly of newly synthesized V1V0-ATPases at the endoplasmic reticulum.

MeSH Terms
Antibodies, Monoclonal Antibody Specificity Arabidopsis Proteins Avena Calcium-Binding Proteins/isolation & purification,metabolism Calnexin Carrier Proteins/metabolism Cell Membrane/enzymology Endoplasmic Reticulum/chemistry Microsomes/chemistry Models, Biological Molecular Chaperones/isolation & purification,metabolism Plant Proteins/metabolism Precipitin Tests Protein Binding Protein Folding Proton-Translocating ATPases/metabolism Solubility Vacuolar Proton-Translocating ATPases
Chemicals
Antibodies, Monoclonal Arabidopsis Proteins Calcium-Binding Proteins Carrier Proteins Molecular Chaperones Plant Proteins BIP protein, Arabidopsis Calnexin Vacuolar Proton-Translocating ATPases Proton-Translocating ATPases
Authors & Affiliations
4 authors, click to expand affiliations / ORCID
Li X
Department of Plant Biology, University of Maryland, College Park 20742, USA.
Su R T
Hsu H T
Sze H
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38 references, click to expand
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Article Info
Journal
The Plant cell
Abbr.
Plant Cell
ISSN
1040-4651
DOI
10.1105/tpc.10.1.119
Published
1998-01-00
Pages
119-30
Language
English
Region
England
NLM ID
9208688
PMCID
PMC143936
Subset
IM
External Links
PubMed source DOI: 10.1105/tpc.10.1.119 PMC Full Text View journal details
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