Parafusin, an exocytic-sensitive phosphoprotein, is the primary acceptor for the glucosylphosphotransferase in Paramecium tetraurelia and rat liver

Birgit H. Satir, Chantragan Srisomsap, Milaniya Reichman, Richard B. Marchase

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Parafusin, the major protein in Paramecium tetraurelia to undergo dephosphorylation in response to secretory stimuli, appears to be the primary acceptor for the glucosylphosphotransferase in this species based on five independent criteria: identical molecular size of 63 kD; identical isoelectric points in the phosphorylated state of pH 5.8 and 6.2; identical behavior in reverse-phase chromatography; immunological cross-reactivity with an affinity-purified anti-parafusin antibody; the presence of a phosphorylated sugar after acid hydrolysis. It appears likely that the dephosphorylation observed with secretion reflects the removal of αGlc-1-P from parafusin's oligosaccharides and is consistent, therefore, with a regulatory role for this cytoplasmic glycosylation event. The glucosylphosphotransferase acceptor in rat liver is also immunoprecipitated by the anti-parafusin antibody and is very similar in physical characteristics to the paramecium protein. This conservation suggests a role for parafusin in mammalian exocytosis as well, at a step common to both the regulated and constitutive secretory pathways.

Original languageEnglish (US)
Pages (from-to)901-907
Number of pages7
JournalJournal of Cell Biology
Issue number3
Publication statusPublished - Sep 1990


ASJC Scopus subject areas

  • Cell Biology

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