Neutralization of pH in the Golgi apparatus causes redistribution of glycosyltransferases and changes in the O-glycosylation of mucins.
Artikel i vetenskaplig tidskrift, 2001

Addition of the weak base ammonium chloride (NH4Cl) or the proton pump inhibitor bafilomycin A1 to cultured HeLa and LS 174T cells effectively neutralized the pH gradient of the secretory pathway. This resulted in relocalization of the three studied glycosyltransferases, N-acetylgalactosaminyltransferase 2, beta1,2 N-acetylglucosaminyltransferase I, and beta1,4 galactosyltransferase 1, normally localized to the Golgi stack, the medial/trans-Golgi and the trans-Golgi/TGN, respectively. Indirect immunofluorescence microscopy, immunoelectron microscopy, and subcellular fractionation of the tagged or native glycosyltransferases showed that NH4Cl caused a relocalization of the enzymes mainly to vesicles of endosomal type, whereas bafilomycin A1 gave mainly cell surface staining. The general morphology of the endoplasmic reticulum and Golgi apparatus was retained as judged from immunofluorescence and electron microscopy studies. When the O-glycans on the guanidinium chloride insoluble gel-forming mucins from the LS 174T cells were analyzed by gas chromatography-mass spectrometry after neutralization of the secretory pathway pH by NH4Cl over 10 days shorter O-glycans were observed. However, no decrease in the number of oligosaccharide chains was indicated. Together, the results suggest that pH is a contributing factor for proper steady-state distribution of glycosyltransferases over the Golgi apparatus and that altered pH may cause alterations in glycosylation possibly due to a relocalization of glycosyltransferases.

enzymology

drug effects

Cultured

drug effects

pharmacology

metabolism

Glycosyltransferases

drug effects

Mucins

Anti-Bacterial Agents

Hela Cells

Macrolides

Cell Compartmentation

Golgi Apparatus

Endosomes

metabolism

Hydrogen-Ion Concentration

drug effects

chemistry

Tumor Cells

Humans

enzymology

drug effects

pharmacology

metabolism

Glycosylation

Ammonium Chloride

Författare

Magnus A. B. Axelsson

Göteborgs universitet

Niclas G. Karlsson

Göteborgs universitet

Daniella Steel

Göteborgs universitet

J Ouwendijk

Tommy Nilsson

Gunnar C. Hansson

Göteborgs universitet

Glycobiology

0959-6658 (ISSN) 1460-2423 (eISSN)

Vol. 11 8 633-44

Ämneskategorier

Medicinsk bioteknologi (med inriktning mot cellbiologi (inklusive stamcellsbiologi), molekylärbiologi, mikrobiologi, biokemi eller biofarmaci)

DOI

10.1093/glycob/11.8.633

PubMed

11479274