scholarly journals ARFGAP1 plays a central role in coupling COPI cargo sorting with vesicle formation

2005 ◽  
Vol 168 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Stella Y. Lee ◽  
Jia-Shu Yang ◽  
Wanjin Hong ◽  
Richard T. Premont ◽  
Victor W. Hsu
Keyword(s):  
Critical Role ◽  
Vesicle Formation ◽  
Golgi Membrane ◽  
Gtpase Activating Protein ◽  
Direct Role ◽  
Effector Functions ◽  
Cargo Proteins ◽  
Adp Ribosylation Factor ◽  
Prevailing View ◽  
Cargo Sorting

Examining how key components of coat protein I (COPI) transport participate in cargo sorting, we find that, instead of ADP ribosylation factor 1 (ARF1), its GTPase-activating protein (GAP) plays a direct role in promoting the binding of cargo proteins by coatomer (the core COPI complex). Activated ARF1 binds selectively to SNARE cargo proteins, with this binding likely to represent at least a mechanism by which activated ARF1 is stabilized on Golgi membrane to propagate its effector functions. We also find that the GAP catalytic activity plays a critical role in the formation of COPI vesicles from Golgi membrane, in contrast to the prevailing view that this activity antagonizes vesicle formation. Together, these findings indicate that GAP plays a central role in coupling cargo sorting and vesicle formation, with implications for simplifying models to describe how these two processes are coupled during COPI transport.

scholarly journals ARFGAP1 promotes the formation of COPI vesicles, suggesting function as a component of the coat

2002 ◽  
Vol 159 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Jia-Shu Yang ◽  
Stella Y. Lee ◽  
Minggeng Gao ◽  
Sylvain Bourgoin ◽  
Paul A. Randazzo ◽  
...  
Keyword(s):  
Coat Protein ◽  
Gap Functions ◽  
Vesicle Formation ◽  
Golgi Membrane ◽  
Gtpase Activating Protein ◽  
Cargo Proteins ◽  
Adp Ribosylation Factor ◽  
Soluble Components ◽  
Cargo Sorting

The role of GTPase-activating protein (GAP) that deactivates ADP-ribosylation factor 1 (ARF1) during the formation of coat protein I (COPI) vesicles has been unclear. GAP is originally thought to antagonize vesicle formation by triggering uncoating, but later studies suggest that GAP promotes cargo sorting, a process that occurs during vesicle formation. Recent models have attempted to reconcile these seemingly contradictory roles by suggesting that cargo proteins suppress GAP activity during vesicle formation, but whether GAP truly antagonizes coat recruitment in this process has not been assessed directly. We have reconstituted the formation of COPI vesicles by incubating Golgi membrane with purified soluble components, and find that ARFGAP1 in the presence of GTP promotes vesicle formation and cargo sorting. Moreover, the presence of GTPγS not only blocks vesicle uncoating but also vesicle formation by preventing the proper recruitment of GAP to nascent vesicles. Elucidating how GAP functions in vesicle formation, we find that the level of GAP on the reconstituted vesicles is at least as abundant as COPI and that GAP binds directly to the dilysine motif of cargo proteins. Collectively, these findings suggest that ARFGAP1 promotes vesicle formation by functioning as a component of the COPI coat.

scholarly journals Clathrin-mediated endocytosis in AP-2–depleted cells

2003 ◽  
Vol 162 (5) ◽  
pp. 909-918 ◽  
Author(s):  
Alison Motley ◽  
Nicholas A. Bright ◽  
Matthew N.J. Seaman ◽  
Margaret S. Robinson
Keyword(s):  
Plasma Membrane ◽  
Transferrin Receptor ◽  
Ldl Receptor ◽  
Coated Vesicle ◽  
Vesicle Formation ◽  
Golgi Membrane ◽  
Coated Pits ◽  
Ldl Receptors ◽  
Cargo Proteins ◽  
Membrane Compartments

We have used RNA interference to knock down the AP-2 μ2 subunit and clathrin heavy chain to undetectable levels in HeLaM cells. Clathrin-coated pits associated with the plasma membrane were still present in the AP-2–depleted cells, but they were 12-fold less abundant than in control cells. No clathrin-coated pits or vesicles could be detected in the clathrin-depleted cells, and post-Golgi membrane compartments were swollen. Receptor-mediated endocytosis of transferrin was severely inhibited in both clathrin- and AP-2–depleted cells. Endocytosis of EGF, and of an LDL receptor chimera, were also inhibited in the clathrin-depleted cells; however, both were internalized as efficiently in the AP-2–depleted cells as in control cells. These results indicate that AP-2 is not essential for clathrin-coated vesicle formation at the plasma membrane, but that it is one of several endocytic adaptors required for the uptake of certain cargo proteins including the transferrin receptor. Uptake of the EGF and LDL receptors may be facilitated by alternative adaptors.

scholarly journals An ACAP1-containing clathrin coat complex for endocytic recycling

2007 ◽  
Vol 178 (3) ◽  
pp. 453-464 ◽  
Author(s):  
Jian Li ◽  
Peter J. Peters ◽  
Ming Bai ◽  
Jun Dai ◽  
Erik Bos ◽  
...  
Keyword(s):  
Cell Migration ◽  
Glucose Homeostasis ◽  
Glucose Transporter ◽  
Critical Role ◽  
Coat Proteins ◽  
Gtpase Activating Protein ◽  
Endocytic Recycling ◽  
Basic Understanding ◽  
Glucose Transporter Type 4 ◽  
Adp Ribosylation Factor

Whether coat proteins play a widespread role in endocytic recycling remains unclear. We find that ACAP1, a GTPase-activating protein (GAP) for ADP-ribosylation factor (ARF) 6, is part of a novel clathrin coat complex that is regulated by ARF6 for endocytic recycling in two key physiological settings, stimulation-dependent recycling of integrin that is critical for cell migration and insulin-stimulated recycling of glucose transporter type 4 (Glut4), which is required for glucose homeostasis. These findings not only advance a basic understanding of an early mechanistic step in endocytic recycling but also shed key mechanistic insights into major physiological events for which this transport plays a critical role.

scholarly journals Binding of cargo sorting signals to AP-1 enhances its association with ADP ribosylation factor 1–GTP

2008 ◽  
Vol 180 (3) ◽  
pp. 467-472 ◽  
Author(s):  
Intaek Lee ◽  
Balraj Doray ◽  
Jennifer Govero ◽  
Stuart Kornfeld
Keyword(s):  
Adaptor Protein ◽  
Adenosine Diphosphate ◽  
Core Domain ◽  
Transport Vesicles ◽  
Sorting Signals ◽  
Stable Association ◽  
Golgi Network ◽  
Adp Ribosylation Factor ◽  
Prevailing View ◽  
Cargo Sorting

The adaptor protein AP-1 is the major coat protein involved in the formation of clathrin-coated vesicles at the trans-Golgi network. The prevailing view is that AP-1 recruitment involves coincident binding to multiple low-affinity sites comprising adenosine diphosphate ribosylation factor 1 (Arf-1)–guanosine triphosphate (GTP), cargo sorting signals, and phosphoinositides. We now show that binding of cargo signal peptides to AP-1 induces a conformational change in its core domain that greatly enhances its interaction with Arf-1–GTP. In addition, we provide evidence for cross talk between the dileucine and tyrosine binding sites within the AP-1 core domain such that binding of a cargo signal to one site facilitates binding to the other site. The stable association of AP-1 with Arf-1–GTP, which is induced by cargo signals, would serve to provide sufficient time for adaptor polymerization and clathrin recruitment while ensuring the packaging of cargo molecules into the forming transport vesicles.

scholarly journals Did2 coordinates Vps4-mediated dissociation of ESCRT-III from endosomes

2006 ◽  
Vol 175 (5) ◽  
pp. 715-720 ◽  
Author(s):  
Daniel P. Nickerson ◽  
Matthew West ◽  
Greg Odorizzi
Keyword(s):  
Vesicle Formation ◽  
Multivesicular Bodies ◽  
Vesicle Budding ◽  
Endosomal Sorting ◽  
Essential Step ◽  
Adenosine Triphosphatases ◽  
Cargo Proteins ◽  
Endosomal Membranes ◽  
Cargo Sorting

The sorting of transmembrane cargo proteins into the lumenal vesicles of multivesicular bodies (MVBs) depends on the recruitment of endosomal sorting complexes required for transport (ESCRTs) to the cytosolic face of endosomal membranes. The subsequent dissociation of ESCRT complexes from endosomes requires Vps4, a member of the AAA family of adenosine triphosphatases. We show that Did2 directs Vps4 activity to the dissociation of ESCRT-III but has no role in the dissociation of ESCRT-I or -II. Surprisingly, vesicle budding into the endosome lumen occurs in the absence of Did2 function even though Did2 is required for the efficient sorting of MVB cargo proteins into lumenal vesicles. This uncoupling of MVB cargo sorting and lumenal vesicle formation suggests that the Vps4-mediated dissociation of ESCRT-III is an essential step in the sorting of cargo proteins into MVB vesicles but is not a prerequisite for the budding of vesicles into the endosome lumen.

scholarly journals GTPase cross talk regulates TRAPPII activation of Rab11 homologues during vesicle biogenesis

2016 ◽  
Vol 215 (4) ◽  
pp. 499-513 ◽  
Author(s):  
Laura L. Thomas ◽  
J. Christopher Fromme
Keyword(s):  
Cross Talk ◽  
Vesicle Formation ◽  
Nucleotide Exchange ◽  
Endocytic Recycling ◽  
Direct Role ◽  
Definitive Evidence ◽  
Nucleotide Exchange Factor ◽  
Vesicle Biogenesis ◽  
Simultaneous Activation ◽  
Bona Fide

Rab guanosine triphosphatases (GTPases) control cellular trafficking pathways by regulating vesicle formation, transport, and tethering. Rab11 and its paralogs regulate multiple secretory and endocytic recycling pathways, yet the guanine nucleotide exchange factor (GEF) that activates Rab11 in most eukaryotic cells is unresolved. The large multisubunit transport protein particle (TRAPP) II complex has been proposed to act as a GEF for Rab11 based on genetic evidence, but conflicting biochemical experiments have created uncertainty regarding Rab11 activation. Using physiological Rab-GEF reconstitution reactions, we now provide definitive evidence that TRAPPII is a bona fide GEF for the yeast Rab11 homologues Ypt31/32. We also uncover a direct role for Arf1, a distinct GTPase, in recruiting TRAPPII to anionic membranes. Given the known role of Ypt31/32 in stimulating activation of Arf1, a bidirectional cross talk mechanism appears to drive biogenesis of secretory and endocytic recycling vesicles. By coordinating simultaneous activation of two essential GTPase pathways, this mechanism ensures recruitment of the complete set of effectors needed for vesicle formation, transport, and tethering.

scholarly journals Rha1, an Arabidopsis Rab5 Homolog, Plays a Critical Role in the Vacuolar Trafficking of Soluble Cargo Proteins

2003 ◽  
Vol 15 (5) ◽  
pp. 1057-1070 ◽  
Author(s):  
Eun Ju Sohn ◽  
Eol Sun Kim ◽  
Min Zhao ◽  
Soo Jin Kim ◽  
Hyeran Kim ◽  
...  
Keyword(s):  
Critical Role ◽  
Cargo Proteins ◽  
Vacuolar Trafficking

scholarly journals Involvement of a novel ADP-ribosylation factor GTPase-activating protein, SMAP, in membrane trafficking: Implications in cancer cell biology

2006 ◽  
Vol 97 (9) ◽  
pp. 801-806 ◽  
Author(s):  
Kenji Tanabe ◽  
Shunsuke Kon ◽  
Waka Natsume ◽  
Tetsuo Torii ◽  
Toshio Watanabe ◽  
...  
Keyword(s):  
Cancer Cell ◽  
Membrane Trafficking ◽  
Cell Biology ◽  
Gtpase Activating Protein ◽  
Adp Ribosylation ◽  
Adp Ribosylation Factor

scholarly journals A Class I ADP-Ribosylation Factor GTPase-Activating Protein Is Critical for Maintaining Directional Root Hair Growth in Arabidopsis

2008 ◽  
Vol 147 (4) ◽  
pp. 1659-1674 ◽  
Author(s):  
Cheol-Min Yoo ◽  
Jiangqi Wen ◽  
Christy M. Motes ◽  
J. Alan Sparks ◽  
Elison B. Blancaflor
Keyword(s):  
Root Hair ◽  
Hair Growth ◽  
Class I ◽  
Gtpase Activating Protein ◽  
Adp Ribosylation ◽  
Root Hair Growth ◽  
Adp Ribosylation Factor
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