Document Detail

Two-step glycosylation of the contact site A protein of Dictyostelium discoideum and transport of an incompletely glycosylated form to the cell surface.
MedLine Citation:
PMID:  3316223     Owner:  NLM     Status:  MEDLINE    
Two different types of oligosaccharides, designated type 1 and 2 carbohydrate residues, are present on the contact site A molecule, an 80-kDa glycoprotein involved in the formation of EDTA-stable cell adhesion during cell aggregation in Dictyostelium discoideum. The first precursor detected by pulse-chase labeling with [35S]methionine was a 68-kDa glycoprotein carrying type 1 carbohydrate. Conversion of the precursor into the 80-kDa form occurred simultaneously with the addition of type 2 carbohydrate. Tunicamycin inhibited type 1 glycosylation more efficiently than type 2 glycosylation. The first precursor detected in tunicamycin-treated cells by pulse-chase labeling was a 53-kDa protein lacking both carbohydrates, which was converted through addition of type 2 carbohydrate into a 66-kDa final product. Labeling of intact cells indicated that this 66-kDa glycoprotein is transported to the cell surface. Prolonged treatment with tunicamycin resulted in the accumulation within the cells of the 53-kDa precursor with no detectable exposure of this protein on the cell surface. It is concluded that type 1 carbohydrate, which is cotranslationally added in N-glycosidic linkages, is neither required for transport of the protein to the Golgi apparatus nor for type 2 glycosylation or protection of the protein against proteolytic degradation. Incapability of tunicamycin-treated cells of forming EDTA-stable cell contacts suggests a role for type 1 carbohydrate in cell adhesion. Type 2 carbohydrate is added posttranslationally. It is required in the absence of type 1 glycosylation for transport of the protein to the cell surface.
H P Hohmann; S Bozzaro; M Yoshida; R Merkl; G Gerisch
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  262     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1987 Dec 
Date Detail:
Created Date:  1988-01-12     Completed Date:  1988-01-12     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  16618-24     Citation Subset:  IM    
Max-Planck-Institut für Biochemie, Martinsried bei München, Federal Republic of Germany.
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MeSH Terms
Antibodies, Monoclonal
Biological Transport, Active
Carbohydrates / analysis
Concanavalin A / metabolism
Dictyostelium / analysis*
Fluorescent Antibody Technique
Molecular Weight
Surface Properties
Viral Proteins / metabolism*
Wheat Germ Agglutinins / metabolism
Reg. No./Substance:
0/Antibodies, Monoclonal; 0/Carbohydrates; 0/Viral Proteins; 0/Wheat Germ Agglutinins; 11028-71-0/Concanavalin A

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