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This Article Full Text Full Text (PDF) All Versions of this Article: 294/6/C1485    most recent 00010.2008v2 00010.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Styers, M. L. Articles by Sztul, E. Search for Related Content PubMed PubMed Citation Articles by Styers, M. L. Articles by Sztul, E.

PROTEIN AND VESICLE TRAFFICKING, CYTOSKELETON

Depletion of β-COP reveals a role for COP-I in compartmentalization of secretory compartments and in biosynthetic transport of caveolin-1

¹Department of Cell Biology, University of Alabama at Birmingham, Birmingham, Alabama; ²Pulmonary, Critical Care and Sleep Medicine, Davis Heart and Lung Research Institute, the Ohio State University Medical Center, Columbus, Ohio

Submitted 9 January 2008 ; accepted in final form 25 March 2008

We have utilized small interfering RNA (siRNA)-mediated depletion of the β-COP subunit of COP-I to explore COP-I function in organellar compartmentalization and protein traffic. Reduction in β-COP levels causes the colocalization of markers for the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC), Golgi, trans-Golgi network (TGN), and recycling endosomes in large, globular compartments. The lack of spatial differentiation of these compartments is not due to a general collapse of all cellular organelles since markers for the early endosomes and lysosomes do not redistribute to the common structures. Anterograde trafficking of the transmembrane cargo vesicular stomatitis virus membrane glycoprotein and of a subset of soluble cargoes is arrested within the common globular compartments. Similarly, recycling traffic of transferrin through the common compartment is perturbed. Furthermore, the trafficking of caveolin-1 (Cav1), a structural protein of caveolae, is arrested within the globular structures. Importantly, Cav1 coprecipitates with the -subunit of COP-I, suggesting that Cav1 is a COP-I cargo. Our findings suggest that COP-I is required for the compartmentalization of the ERGIC, Golgi, TGN, and recycling endosomes and that COP-I plays a novel role in the biosynthetic transport of Cav1.

Golgi; trans-Golgi network; endoplasmic reticulum-Golgi intermediate compartment; recycling endosome; coatomer

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