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RICIN‐BINDING PROTEINS ALONG THE ENDOCYTIC PATHWAY: THE MAJOR ENDOSOMAL RICIN‐BINDING PROTEIN IS ENDOSOME‐SPECIFIC
Author(s) -
ALAMI MÉRIEM,
TAUPIAC MARIEPIERRE,
BEAUMELLE BRUNO
Publication year - 1997
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1006/cbir.1996.0120
Subject(s) - ricin , endosome , endocytic cycle , endocytosis , glycoprotein , microbiology and biotechnology , lectin , cytosol , biochemistry , biology , chemistry , cell , enzyme , toxin
Ricin is internalized after binding at the cell surface via lectin activity of the B‐chain recognizing terminal galactose residues. Ricin‐A chain is then translocated to the cytosol from various endocytic structures. Cell death is the result of catalytic inactivation of protein synthesis. Using 125 I‐ricin overlays, we examined the distribution of ricin binding‐proteins within highly purified preparations of plasma membrane vesicles, endosomes and lysosomes from lymphocytes. All compartments of the endocytic pathway had distinct profiles; some ricin‐binding proteins were present throughout the pathway; others were restricted to the plasma membrane and endosomes. The major endosomal protein recognized by 125 I‐ricin, a 166kDa glycoprotein, was endosome‐specific. When endosomal proteins were solubilized before chromatography onto ricin‐agarose this protein was also by far the major specifically‐bound glycoprotein. This 166 kDa glycoprotein might be involved in ricin translocation from this compartment.