RRC ID 1870
Author Stefano G, Renna L, Chatre L, Hanton SL, Moreau P, Hawes C, Brandizzi F.
Title In tobacco leaf epidermal cells, the integrity of protein export from the endoplasmic reticulum and of ER export sites depends on active COPI machinery.
Journal Plant J
Abstract Trafficking of secretory proteins between the endoplasmic reticulum (ER) and the Golgi apparatus depends on coat protein complexes I (COPI) and II (COPII) machineries. To date, full characterization of the distribution and dynamics of these machineries in plant cells remains elusive. Furthermore, except for a presumed linkage between COPI and COPII for the maintenance of ER protein export, the mechanisms by which COPI influences COPII-mediated protein transport from the ER in plant cells are largely uncharacterized. Here we dissect the dynamics of COPI in intact cells using live-cell imaging and fluorescence recovery after photobleaching analyses to provide insights into the distribution of COPI and COPII machineries and the mechanisms by which COPI influences COPII-mediated protein export from the ER. We found that Arf1 and coatomer are dynamically associated with the Golgi apparatus and that the COPII coat proteins Sec24 and Sec23 localize at ER export sites that track with the Golgi apparatus in tobacco leaf epidermal cells. Arf1 is also localized at additional structures that originate from the Golgi apparatus but that lack coatomer, supporting the model that Arf1 also has a coatomer-independent role for post-Golgi protein transport in plants. When ER to Golgi protein transport is inhibited by mutations that hamper Arf1-GTPase activity without directly disrupting the COPII machinery for ER protein export, Golgi markers are localized in the ER and the punctate distribution of Sec24 and Sec23 at the ER export sites is lost. These findings suggest that Golgi membrane protein distribution is maintained by the balanced action of COPI and COPII systems, and that Arf1-coatomer is most likely indirectly required for forward trafficking out of the ER due to its role in recycling components that are essential for differentiation of the ER export domains formed by the Sar1-COPII system.
Volume 46(1)
Pages 95-110
Published 2006-4-1
DOI 10.1111/j.1365-313X.2006.02675.x
PMID 16553898
MeSH ADP-Ribosylation Factor 1 / analysis ADP-Ribosylation Factor 1 / metabolism Coat Protein Complex I / physiology* Coatomer Protein / analysis Coatomer Protein / metabolism Endoplasmic Reticulum / metabolism* GTP Phosphohydrolases / genetics Golgi Apparatus / metabolism Membrane Proteins / metabolism Membrane Proteins / physiology Plant Leaves / cytology Plant Leaves / metabolism Plant Proteins / metabolism* Plant Proteins / physiology Protein Transport / physiology Tobacco / cytology Tobacco / metabolism*
IF 6.141
Times Cited 78
Arabidopsis / Cultured plant cells, genes pda00962