Linked Life Data

1533633

Source:http://linkedlifedata.com/resource/pubmed/id/1533633

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
14
pubmed:dateCreated
1992-6-9
pubmed:abstractText
The glycosylation and subsequent phosphorylation of mannose residues is a pivotal modification during the biosynthesis of lysosomal enzymes. We have identified the sites of N-linked glycosylation and oligosaccharide phosphorylation on the alpha-subunit of beta-hexosaminidase and have determined the influence of the oligosaccharides on the folding and transport of the enzyme. The potential glycosylation sequences, either singly or in combination, were eliminated through site-directed mutagenesis of the cDNA. By expression of the mutant cDNAs in COS-1 cells, each of the three glycosylation sites on the alpha-subunit was found to be modified by an oligosaccharide. One of the three oligosaccharides was the preferred site of phosphorylation. The absence of any individual oligosaccharide did not diminish the expression of the catalytic activity associated with the alpha-chain, implying proper folding and assembly of subunits. A profound effect was observed, however, when all three oligosaccharides were absent. The unglycosylated alpha-subunit, resulting from genetic alteration of all three glycosylation sites or synthesis of the wild-type protein in the presence of tunicamycin, was catalytically inactive. It was found to be improperly folded into an insoluble aggregate, linked through inappropriate disulfide bonds. The unglycosylated protein was trapped in the lumen of the endoplasmic reticulum and was found in a complex with the Ig heavy chain-binding protein, BiP. The properties of the nonglycosylated, misfolded alpha-subunit were similar to some mutant alpha-subunits in Tay-Sachs disease patients. The results indicate that the oligosaccharides are essential, although not in a site-specific manner, for proper folding and cellular transport of the alpha-subunit.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
267
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
10039-44
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed-meshheading:1533633-Amino Acid Sequence, pubmed-meshheading:1533633-Animals, pubmed-meshheading:1533633-Antibodies, pubmed-meshheading:1533633-Base Sequence, pubmed-meshheading:1533633-Cell Line, pubmed-meshheading:1533633-Codon, pubmed-meshheading:1533633-Glycosylation, pubmed-meshheading:1533633-Immunohistochemistry, pubmed-meshheading:1533633-Lysosomes, pubmed-meshheading:1533633-Macromolecular Substances, pubmed-meshheading:1533633-Molecular Sequence Data, pubmed-meshheading:1533633-Mutagenesis, Site-Directed, pubmed-meshheading:1533633-Oligodeoxyribonucleotides, pubmed-meshheading:1533633-Oligopeptides, pubmed-meshheading:1533633-Phosphorylation, pubmed-meshheading:1533633-Protein Processing, Post-Translational, pubmed-meshheading:1533633-Sequence Homology, Nucleic Acid, pubmed-meshheading:1533633-Transfection, pubmed-meshheading:1533633-beta-N-Acetylhexosaminidases
pubmed:year
1992
pubmed:articleTitle
Analysis of the glycosylation and phosphorylation of the alpha-subunit of the lysosomal enzyme, beta-hexosaminidase A, by site-directed mutagenesis.
pubmed:affiliation
Genetics and Biochemistry Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
pubmed:publicationType
Journal Article, Comparative Study