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A phorbol ester‐binding protein is required downstream of Rab5 in endosome fusion
Author(s) -
Aballay Alejandro,
Barbieri M.Alejandro,
Colombo Marı́a I,
Arenas Graciela N,
Stahl Philip D,
Mayorga Luis S
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01579-8
Subject(s) - endosome , protein kinase c , phorbol , fusion protein , chemistry , lipid bilayer fusion , cytosol , calphostin c , microbiology and biotechnology , biochemistry , recombinant dna , biology , phosphorylation , receptor , enzyme , membrane , gene
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.