Ricin A chain without its partner B chain is degraded after retrotranslocation from the endoplasmic reticulum to the cytosol in plant cells
UNSPECIFIED. (2001) Ricin A chain without its partner B chain is degraded after retrotranslocation from the endoplasmic reticulum to the cytosol in plant cells. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 98 (25). pp. 14726-14731. ISSN 0027-8424Full text not available from this repository.
When expressed in tobacco cells, the catalytic subunit of the dimeric ribosome inactivating protein, ricin, is first inserted into the endoplasmic reticulum (ER) and then degraded in a manner that can be partially inhibited by the proteasome inhibitor clasto-lactacystin beta -lactone. Consistent with the implication of cytosolic proteasomes, degradation of ricin A chain is brefeldin A-insensitive and the polypeptides that accumulate in the presence of the proteasome inhibitor are not processed in a vacuole-specific fashion. Rather, these stabilized polypeptides are in part deglycosylated by a peptide:N-glycanase-like activity. Taken together, these results indicate that ricin A chain, albeit a structurally native protein, can behave as a substrate for ER to cytosol export, deglycosylation in the cytosol, and proteasomal degradation. Furthermore, retrotranslocation of this protein is not tightly coupled to proteasomal activity. These data are consistent with the hypothesis that ricin A chain can exploit the ER-associated protein degradation pathway to reach the cytosol. Although well characterized in mammalian and yeast cells, the operation of a similar pathway to the cytosol of plant cells has not previously been demonstrated.
|Item Type:||Journal Article|
|Journal or Publication Title:||PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA|
|Publisher:||NATL ACAD SCIENCES|
|Date:||4 December 2001|
|Number of Pages:||6|
|Page Range:||pp. 14726-14731|
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