The Sar1 GTPase coordinates biosynthetic cargo selection with endoplasmic reticulum export site assembly


Aridor, M; Fish, KN; Bannykh, S; Weissman, J; Roberts, TH; Lippincott-Schwartz, J; Balch, WE; (2001) The Sar1 GTPase coordinates biosynthetic cargo selection with endoplasmic reticulum export site assembly. The Journal of cell biology, 152 (1). pp. 213-29. ISSN 0021-9525 DOI: https://doi.org/10.1083/jcb.152.1.213

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Abstract

Cargo selection and export from the endoplasmic reticulum is mediated by the COPII coat machinery that includes the small GTPase Sar1 and the Sec23/24 and Sec13/31 complexes. We have analyzed the sequential events regulated by purified Sar1 and COPII coat complexes during synchronized export of cargo from the ER in vitro. We find that activation of Sar1 alone, in the absence of other cytosolic components, leads to the formation of ER-derived tubular domains that resemble ER transitional elements that initiate cargo selection. These Sar1-generated tubular domains were shown to be transient, functional intermediates in ER to Golgi transport in vitro. By following cargo export in live cells, we show that ER export in vivo is also characterized by the formation of dynamic tubular structures. Our results demonstrate an unanticipated and novel role for Sar1 in linking cargo selection with ER morphogenesis through the generation of transitional tubular ER export sites.

Item Type: Article
Keywords: Animal, Biological Transport, COP-Coated Vesicles/metabolism, Cytoplasm/metabolism, Endoplasmic Reticulum/*metabolism, Enzyme Activation, Fluorescence, Golgi Apparatus/metabolism, Intracellular Membranes/metabolism, Microscopy, Video, Monomeric GTP-Binding Proteins/*metabolism, Support, Non-U.S. Gov't, Support, U.S. Gov't, P.H.S., Time Factors, Viral Envelope Proteins/metabolism, Animals, Biological Transport, COP-Coated Vesicles, metabolism, Cytoplasm, metabolism, Endoplasmic Reticulum, metabolism, Enzyme Activation, Fluorescence, Golgi Apparatus, metabolism, Intracellular Membranes, metabolism, Membrane Glycoproteins, Microscopy, Video, Monomeric GTP-Binding Proteins, metabolism, Saccharomyces cerevisiae Proteins, Support, Non-U.S. Gov't, Support, U.S. Gov't, P.H.S., Time Factors, Viral Envelope Proteins, metabolism
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Immunology and Infection
PubMed ID: 11149932
Web of Science ID: 166367100018
URI: http://researchonline.lshtm.ac.uk/id/eprint/15632

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