Document Detail

Restricted processing of glycans by endomannosidase in mammalian cells.
MedLine Citation:
PMID:  22641772     Owner:  NLM     Status:  Publisher    
Removal of α-glucose residues from nascent glycoproteins in the early secretory pathway is a requirement for further N-glycan maturation. While for most glycoproteins deglucosylation is a stepwise process mediated by endoplasmic reticulum-associated glucosidases I and II, Golgi endo-α-mannosidase provides a backup mechanism for glycoprotein deglucosylation. Although conserved in mammals, in certain cell lines endomannosidase activity in vitro appears to differ from its activity in cells following glucosidase inhibition. Here, we show that in bovine cells this is explained by restricted substrate specificity allowing processing of Glc(1)Man(7)GlcNAc(1/2) and Glc(1)Man(5)GlcNAc(1/2) but not fully glucosylated glycans that build up when glucosidases are inhibited. Our data further demonstrate that such specificity is determined genetically rather than post-translationally. We also demonstrate that the bovine endomannosidase is transcriptionally upregulated by comparison with glucosidase II in MDBK cells and speculate that this is to compensate for the reduced catalytic activity as measured in the recombinant form of the enzyme.
Nikolay V Kukushkin; Iona S Easthope; Dominic S Alonzi; Terry D Butters
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-5-28
Journal Detail:
Title:  Glycobiology     Volume:  -     ISSN:  1460-2423     ISO Abbreviation:  -     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-5-29     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9104124     Medline TA:  Glycobiology     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, UK.
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