Analysis of intracellular translocation of glycoproteins using inhibitors as probes

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Specific inhibitors are expected to be useful probes in analysis of the mechanism of intracellular translocation of glycoproteins. Very restricted are such inhibitors at present. Novel inhibitors have been searched for by a newly established screening method.Many of the compounds isolated in this study were found to inhibit specifically the V-type ATPase among H^+-translocating ATPases. In the presence of such a compounds, cell surface expression of virus glycoprotein was greatly suppressed and accumulated intracellularly. The site(s) of blockade was indicated to be before or at the Golgi by analysing the structure of the N-glycosidically bound oligosaccharide moiety. On the contrary, invertase secretion to the periplasm and targetting of carboxypeptidase Y to the vacuole in Saccharomyces cerevisiae were not affected in spite of the fact the saccharide moiety of these glycoproteins was immaturely processed in the presence of inhibitor of V-type ATPase.The already reported novel blockade by brefeldin was partly reversed by nocadazole, suggesting that induction of the retrograde trafficking from the Golgi to endoplasmic reticulum is the cause of the blockade of cell surface expression of virus glycoprotein.