scholarly journals Reconstitution of Coat Protein Complex II (COPII) Vesicle Formation from Cargo-reconstituted Proteoliposomes Reveals the Potential Role of GTP Hydrolysis by Sar1p in Protein Sorting

2003 ◽  
Vol 279 (2) ◽  
pp. 1330-1335 ◽  
Author(s):  
Ken Sato ◽  
Akihiko Nakano
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Potential Role ◽  
Protein Sorting ◽  
Vesicle Formation ◽  
Gtp Hydrolysis ◽  
Complex Ii ◽  
Copii Vesicle ◽  
Coat Protein Complex

scholarly journals Not just a cargo receptor for large cargoes; an emerging role of TANGO1 as an organizer of ER exit sites

2019 ◽  
Vol 166 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Kota Saito ◽  
Miharu Maeda
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Vesicle Formation ◽  
Wide Range ◽  
Copii Vesicle ◽  
Cargo Receptor ◽  
Er Exit Sites ◽  
Golgi Organization

Abstract Proteins synthesized within the endoplasmic reticulum (ER) are exported from ER exit sites via coat protein complex II (COPII)-coated vesicles. Although the mechanisms of COPII-vesicle formation at the ER exit sites are highly conserved among species, vertebrate cells secrete a wide range of materials, including collagens and chylomicrons, which form bulky structures within the ER that are too large to fit into conventional carriers. Transport ANd Golgi Organization 1 (TANGO1) was initially identified as a cargo receptor for collagens but has been recently rediscovered as an organizer of ER exit sites. We would like to review recent advances in the mechanism of large cargo secretion and organization of ER exit sites through the function of TANGO1.

scholarly journals Expression of Sar1b Enhances Chylomicron Assembly and Key Components of the Coat Protein Complex II System Driving Vesicle Budding

2011 ◽  
Vol 31 (11) ◽  
pp. 2692-2699 ◽  
Author(s):  
Emile Levy ◽  
Elodie Harmel ◽  
Martine Laville ◽  
Rocio Sanchez ◽  
Léa Emonnot ◽  
...  
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Vesicle Budding ◽  
Complex Ii ◽  
Coat Protein Complex

scholarly journals Nm23H2 Facilitates Coat Protein Complex II Assembly and Endoplasmic Reticulum Export in Mammalian Cells

2005 ◽  
Vol 16 (2) ◽  
pp. 835-848 ◽  
Author(s):  
Lori Kapetanovich ◽  
Cassandra Baughman ◽  
Tina H. Lee
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Protein Complex ◽  
Mammalian Cells ◽  
Complex Ii ◽  
Permeabilized Cells ◽  
Er Export ◽  
Coat Protein Complex

The cytosolic coat protein complex II (COPII) mediates vesicle formation from the endoplasmic reticulum (ER) and is essential for ER-to-Golgi trafficking. The minimal machinery for COPII assembly is well established. However, additional factors may regulate the process in mammalian cells. Here, a morphological COPII assembly assay using purified COPII proteins and digitonin-permeabilized cells has been applied to demonstrate a role for a novel component of the COPII assembly pathway. The factor was purified and identified by mass spectrometry as Nm23H2, one of eight isoforms of nucleoside diphosphate kinase in mammalian cells. Importantly, recombinant Nm23H2, as well as a catalytically inactive version, promoted COPII assembly in vitro, suggesting a noncatalytic role for Nm23H2. Consistent with a function for Nm23H2 in ER export, Nm23H2 localized to a reticular network that also stained for the ER marker calnexin. Finally, an in vivo role for Nm23H2 in COPII assembly was confirmed by isoform-specific knockdown of Nm23H2 by using short interfering RNA. Knockdown of Nm23H2, but not its most closely related isoform Nm23H1, resulted in diminished COPII assembly at steady state and reduced kinetics of ER export. These results strongly suggest a previously unappreciated role for Nm23H2 in mammalian ER export.

Recruitment of coat-protein-complex proteins on to phagosomal membranes is regulated by a brefeldin A-sensitive ADP-ribosylation factor

2001 ◽  
Vol 355 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Walter BERÓN ◽  
Luis S. MAYORGA ◽  
Maria I. COLOMBO ◽  
Philip D. STAHL
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Brefeldin A ◽  
Type I ◽  
Protein Activity ◽  
Gtp Hydrolysis ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor ◽  
Particle Internalization ◽  
Coat Protein Complex

Particle internalization in macrophages is followed by a complex maturation process. We have previously observed that proteins bound to phagocytosed particles are sorted from phagosomes into a heterogeneous population of vesicles that fuse with endosomes. However, the mechanism and the protein machinery involved in the formation of these phagosome-derived vesicles are largely unknown. It has been shown that vesicles coated with coat protein complex type I (COPI) have a role in both secretion and endocytosis. To address the possibility that COPI proteins might participate in the formation of phagosome-derived vesicles we studied the recruitment of β-COP to highly purified phagosomes. The binding of β-COP to phagosomal membranes was regulated by nucleotides and inhibited by brefeldin A (BFA). An ADP-ribosylation factor 1 (ARF1) mutant defective in GTP hydrolysis supported the binding of β-COP to phagosomes independently of added nucleotide. AlF4 and Gβγ subunits, agents known to modulate heterotrimeric G-protein activity, were tested in the β-COP binding assay. AlF4 increased β-COP association, whereas binding was inhibited by the addition of Gβγ subunits. Our results suggest that COP proteins are recruited to phagosomal membranes by a mechanism that involves heterotrimeric GTP-binding proteins and a BFA-sensitive ARF. In addition, our findings indicate that COPI proteins are involved in the recycling of components from phagosomes to the cell surface.

scholarly journals 2P303 Visualization of COPII vesicle formation process on artificial membrane. : Role of GTP hydrolysis(Native and artificial biomembranes,Oral Presentations)

2007 ◽  
Vol 47 (supplement) ◽  
pp. S188
Author(s):  
Kazuhito V. Tabata ◽  
Ken Sato ◽  
Toru Ide ◽  
Takayuki Nishizaka ◽  
Akihiko Nakano ◽  
...  
Keyword(s):  
Formation Process ◽  
Vesicle Formation ◽  
Artificial Membrane ◽  
Gtp Hydrolysis ◽  
Copii Vesicle ◽  
Oral Presentations

scholarly journals Small sequence variations between two mammalian paralogs of the small GTPase SAR1 underlie functional differences in coat protein complex II assembly

2020 ◽  
Vol 295 (25) ◽  
pp. 8401-8412 ◽  
Author(s):  
David B. Melville ◽  
Sean Studer ◽  
Randy Schekman
Keyword(s):  
Endoplasmic Reticulum ◽  
Coat Protein ◽  
Binding Site ◽  
Protein Complex ◽  
Small Gtpase ◽  
The Other ◽  
Complex Ii ◽  
Gtp Binding ◽  
Lipoprotein Secretion ◽  
Coat Protein Complex

Vesicles that are coated by coat protein complex II (COPII) are the primary mediators of vesicular traffic from the endoplasmic reticulum to the Golgi apparatus. Secretion-associated Ras-related GTPase 1 (SAR1) is a small GTPase that is part of COPII and, upon GTP binding, recruits the other COPII proteins to the endoplasmic reticulum membrane. Mammals have two SAR1 paralogs that genetic data suggest may have distinct physiological roles, e.g. in lipoprotein secretion in the case of SAR1B. Here we identified two amino acid clusters that have conserved SAR1 paralog–specific sequences. We observed that one cluster is adjacent to the SAR1 GTP-binding pocket and alters the kinetics of GTP exchange. The other cluster is adjacent to the binding site for two COPII components, SEC31 homolog A COPII coat complex component (SEC31) and SEC23. We found that the latter cluster confers to SAR1B a binding preference for SEC23A that is stronger than that of SAR1A for SEC23A. Unlike SAR1B, SAR1A was prone to oligomerize on a membrane surface. SAR1B knockdown caused loss of lipoprotein secretion, overexpression of SAR1B but not of SAR1A could restore secretion, and a divergent cluster adjacent to the SEC31/SEC23-binding site was critical for this SAR1B function. These results highlight that small primary sequence differences between the two mammalian SAR1 paralogs lead to pronounced biochemical differences that significantly affect COPII assembly and identify a specific function for SAR1B in lipoprotein secretion, providing insights into the mechanisms of large cargo secretion that may be relevant for COPII-related diseases.

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