Document Detail

Processing of N-linked oligosaccharide depends on its location in the anion exchanger, AE1, membrane glycoprotein.
MedLine Citation:
PMID:  10861210     Owner:  NLM     Status:  MEDLINE    
The human erythrocyte anion exchanger (AE)1 (Band 3) contains a single complex N-linked oligosaccharide that is attached to Asn(642) in the fourth extracellular loop of this polytopic membrane protein, while other isoforms (AE2, AE3 and trout AE1) are N-glycosylated on the preceding extracellular loop. Human AE1 expressed in transfected human embryonic kidney (HEK)-293 or COS-7 cells contained a high-mannose oligosaccharide. The lack of oligosaccharide processing was not due to retention of AE1 in the endoplasmic reticulum since biotinylation assays showed that approx. 30% of the protein was expressed at the cell surface. Moving the N-glycosylation site to the preceding extracellular loop in an AE1 glycosylation mutant (N555) resulted in processing of the oligosaccharide and production of a complex form of AE1. A double N-glycosylation mutant (N555/N642) contained both a high-mannose and a complex oligosaccharide chain. The complex form of the N555 mutant could be biotinylated showing that this form of the glycoprotein was at the cell surface. Pulse-chase experiments showed that the N555 mutant was efficiently converted from a high-mannose to a complex oligosaccharide with a half-time of approx. 4 h, which reflected the time course of trafficking of AE1 from the endoplasmic reticulum to the plasma membrane. The turnover of the complex form of the N555 mutant occurred with a half-life of approx. 15 h. The results show that the oligosaccharide attached to the endogenous site in extracellular loop 4 in human AE1 is not processed in HEK-293 or COS-7 cells, while the oligosaccharide attached to the preceding loop is converted into the complex form.
J Li; J Quilty; M Popov; R A Reithmeier
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  349     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  2000 Jul 
Date Detail:
Created Date:  2001-01-26     Completed Date:  2001-07-19     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  England    
Other Details:
Languages:  eng     Pagination:  51-7     Citation Subset:  IM    
Medical Research Council Group in Membrane Biology, Department of Medicine, Room 7344, Medical Sciences Building, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Antiporters / metabolism*
Binding Sites
COS Cells
Cell Line
Cell Membrane / metabolism
Chloride-Bicarbonate Antiporters
Electrophoresis, Polyacrylamide Gel
Endoplasmic Reticulum / metabolism
Lectins / metabolism
Oligosaccharides / metabolism*
Plasmids / metabolism
Protein Binding
Protein Isoforms
Protein Structure, Tertiary
Sequence Analysis, DNA
Time Factors
Reg. No./Substance:
0/Anions; 0/Antiporters; 0/Chloride-Bicarbonate Antiporters; 0/Lectins; 0/Oligosaccharides; 0/Protein Isoforms

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Acylphosphatase possesses nucleoside triphosphatase and nucleoside diphosphatase activities.
Next Document:  Activation of phosphatidylinositol 3-kinase is required for transcriptional activity of F-type 6-pho...