A phorbol ester-binding protein is required downstream of Rab5 in endosome fusion

Alejandro Aballay, M. Alejandro Barbieri, María I. Colombo, Graciela N. Arenas, Philip D. Stahl, Luis S. Mayorga

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Previous observations indicate that a zinc and phorbol ester binding factor is necessary for endosome fusion. To further characterize the role of this factor in the process, we used an in vitro endosome fusion assay supplemented with recombinant Rab5 proteins. Both zinc depletion and addition of calphostin C, an inhibitor of protein kinase C, inhibited endosome fusion in the presence of active Rab5. Addition of the phorbol ester PMA (phorbol 12-myristate 13-acetate) reversed the inhibition of endosome fusion caused by a Rab5 negative mutant. Moreover, PMA stimulated fusion in the presence of Rab5 immunodepleted cytosol. These results suggest that the phorbol ester binding protein is acting downstream of Rab5 in endosome fusion. Copyright (C) 1998 Federation of European Biochemical Societies.

Original languageEnglish (US)
Pages (from-to)373-378
Number of pages6
JournalFEBS Letters
Issue number3
StatePublished - Dec 28 1998
Externally publishedYes


  • Endocytosis
  • Endosome fusion
  • Phorbol ester
  • Protein kinase C
  • Rab5

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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