Diverse roles for the p24 family of proteins in eukaryotic cells

2012 ◽  
Vol 3 (6) ◽  
pp. 561-570 ◽  
Author(s):  
Irmgard Schuiki ◽  
Allen Volchuk
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Complex I ◽  
Secretory Pathway ◽  
Protein Transport ◽  
Protein Quality ◽  
Eukaryotic Cells ◽  
Type I ◽  
P24 Protein ◽  
Coat Protein Complex

AbstractMembers of the p24 protein family form a highly conserved family of type I transmembrane proteins that are abundant components of the early secretory pathway. Topologically, the proteins have a large luminal domain and a short cytoplasmic domain that allows for targeting to both coat protein complex II and coat protein complex I vesicles, and thus these proteins cycle between the endoplasmic reticulum and Golgi compartments. Several functions have been proposed for these proteins including a role in coat protein complex I vesicle biogenesis, cargo protein selection, organization of intracellular membranes, and protein quality control. Recent studies have added to the list of potential cargo substrates for which p24 function is required for normal transport in the secretory pathway. This review focuses on recent developments in the study of p24 proteins and their requirement for secretory and membrane protein transport in eukaryotic cells.

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.

Coat protein complex I facilitates dengue virus production

2018 ◽  
Vol 250 ◽  
pp. 13-20 ◽  
Author(s):  
Nopprarat Tongmuang ◽  
Umpa Yasamut ◽  
Pucharee Songprakhon ◽  
Thanyaporn Dechtawewat ◽  
Shilu Malakar ◽  
...  
Keyword(s):  
Coat Protein ◽  
Dengue Virus ◽  
Protein Complex ◽  
Complex I ◽  
Virus Production ◽  
Coat Protein Complex

scholarly journals Endomembrane Trafficking in Plants

2020 ◽  
Author(s):  
Birsen Cevher-Keskin
Keyword(s):  
Coat Protein ◽  
Plant Development ◽  
Protein Complex ◽  
Binding Proteins ◽  
Critical Role ◽  
Small Gtpases ◽  
Eukaryotic Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Coat Protein Complex

The functional organization of eukaryotic cells requires the exchange of proteins, lipids, and polysaccharides between membrane compartments through transport intermediates. Small GTPases largely control membrane traffic, which is essential for the survival of all eukaryotes. Transport from one compartment of this pathway to another is mediated by vesicular carriers, which are formed by the controlled assembly of coat protein complexes (COPs) on donor organelles. The activation of small GTPases is essential for vesicle formation from a donor membrane. In eukaryotic cells, small GTP-binding proteins comprise the largest family of signaling proteins. The ADP-ribosylation factor 1 (ARF1) and secretion-associated RAS superfamily 1 (SAR1) GTP-binding proteins are involved in the formation and budding of vesicles throughout plant endomembrane systems. ARF1 has been shown to play a critical role in coat protein complex I (COPI)-mediated retrograde trafficking in eukaryotic systems, whereas SAR1 GTPases are involved in intracellular coat protein complex II (COPII)-mediated protein trafficking from the endoplasmic reticulum (ER) to the Golgi apparatus. The dysfunction of the endomembrane system can affect signal transduction, plant development, and defense. This chapter offers a summary of membrane trafficking system with an emphasis on the role of GTPases especially ARF1, SAR1, and RAB, their regulatory proteins, and interaction with endomembrane compartments. The vacuolar and endocytic trafficking are presented to enhance our understanding of plant development and immunity in plants.

Role of EBAG9 protein in coat protein complex I‐dependent glycoprotein maturation and secretion processes in tumor cells

2010 ◽  
Vol 24 (10) ◽  
pp. 4000-4019 ◽  
Author(s):  
Jana Wolf ◽  
Tatiana A. Remier ◽  
Sebastian Schuck ◽  
Constantin Rüder ◽  
Kerstin Gerlach ◽  
...  
Keyword(s):  
Coat Protein ◽  
Tumor Cells ◽  
Protein Complex ◽  
Complex I ◽  
Coat Protein Complex

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.

scholarly journals Differential roles of ArfGAP1, ArfGAP2, and ArfGAP3 in COPI trafficking

2008 ◽  
Vol 183 (4) ◽  
pp. 725-735 ◽  
Author(s):  
Carolin Weimer ◽  
Rainer Beck ◽  
Priska Eckert ◽  
Ingeborg Reckmann ◽  
Jörg Moelleken ◽  
...  
Keyword(s):  
Coat Protein ◽  
Protein Complex ◽  
Complex I ◽  
Adenosine Diphosphate ◽  
General Function ◽  
Golgi Membrane ◽  
Gtpase Activating Protein ◽  
Gtp Hydrolysis ◽  
Copi Vesicle ◽  
Guanosine Triphosphatase

The formation of coat protein complex I (COPI)–coated vesicles is regulated by the small guanosine triphosphatase (GTPase) adenosine diphosphate ribosylation factor 1 (Arf1), which in its GTP-bound form recruits coatomer to the Golgi membrane. Arf GTPase-activating protein (GAP) catalyzed GTP hydrolysis in Arf1 triggers uncoating and is required for uptake of cargo molecules into vesicles. Three mammalian ArfGAPs are involved in COPI vesicle trafficking; however, their individual functions remain obscure. ArfGAP1 binds to membranes depending on their curvature. In this study, we show that ArfGAP2 and ArfGAP3 do not bind directly to membranes but are recruited via interactions with coatomer. In the presence of coatomer, ArfGAP2 and ArfGAP3 activities are comparable with or even higher than ArfGAP1 activity. Although previously speculated, our results now demonstrate a function for coatomer in ArfGAP-catalyzed GTP hydrolysis by Arf1. We suggest that ArfGAP2 and ArfGAP3 are coat protein–dependent ArfGAPs, whereas ArfGAP1 has a more general function.

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