The role of the AP-1 adaptor complex in trafficking between the trans-Golgi Network and endosomal system

Mapping Intimacies ◽

10.32469/10355/4172 ◽

2005 ◽

Author(s):

◽

Christopher Foote

Keyword(s):

Saccharomyces Cerevisiae ◽

Early Endosome ◽

Trans Golgi Network ◽

Retrieval Mechanism ◽

Prevacuolar Compartment ◽

Golgi Network ◽

In Transit ◽

Endosomal System ◽

Kinetics Of

In Saccharomyces cerevisiae it is generally accepted that there are two routes for trafficking of proteins from the trans-Golgi network (TGN) to the vacuole. One involves direct transport from the TGN to the vacuole. The second involves transport from the TGN to the prevacuolar compartment (PVC) via GGA coated vesicles, followed by PVC to vacuole transport. We propose that there is a third route. This route entails transit from the TGN to the early endosome (EE), followed by delivery to the PVC and vacuole. In support of an alternative route, the processing kinetics of A(F[arrow]A)-ALP are not affected by mutations in the GGA proteins. This is in contrast to proteins that use the GGA pathway, as their delivery to the vacuole is significantly slowed when GGA function is ablated. Further support of an EE itinerary is the observation that A(F[arrow]A)-ALP co localizes with the lipophilic dye, FM4-64 at a time when the dye is associated with the EE. Disruption of the AP-1 vesicle coat complex leads to an accelerated processing of A(F[arrow]A)-ALP. Appending the region of A(F[arrow]A)-ALP that interacts with AP-1 to Cps1p delays its progress to the vacuole. These results are consistent with a model in which A(F[arrow]A)-ALP passes through the EE in transit to the vacuole. A(F[arrow]A)-ALP physically interacts with AP-1, and this interaction delays its delivery to the vacuole. Data presented in this thesis suggests that in Saccharomyces cerevisiae AP-1 functions as a retrieval mechanism from the EE to the TGN.

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Yeast Golgi-localized, γ-Ear–containing, ADP-Ribosylation Factor-binding Proteins Are but Adaptor Protein-1 Is Not Required for Cell-free Transport of Membrane Proteins from the Trans-Golgi Network to the Prevacuolar Compartment

Molecular Biology of the Cell ◽

10.1091/mbc.e07-05-0442 ◽

2008 ◽

Vol 19 (11) ◽

pp. 4826-4836 ◽

Cited By ~ 16

Author(s):

Mohamed E. Abazeed ◽

Robert S. Fuller

Keyword(s):

Binding Proteins ◽

Adaptor Protein ◽

Early Endosome ◽

Dominant Negative ◽

Factor Binding ◽

Trans Golgi Network ◽

Direct Pathway ◽

Prevacuolar Compartment ◽

Golgi Network ◽

Adp Ribosylation Factor

Golgi-localized, γ-Ear–containing, ADP-ribosylation factor-binding proteins (GGAs) and adaptor protein-1 (AP-1) mediate clathrin-dependent trafficking of transmembrane proteins between the trans-Golgi network (TGN) and endosomes. In yeast, the vacuolar sorting receptor Vps10p follows a direct pathway from the TGN to the late endosome/prevacuolar compartment (PVC), whereas, the processing protease Kex2p partitions between the direct pathway and an indirect pathway through the early endosome. To examine the roles of the Ggas and AP-1 in TGN–PVC transport, we used a cell-free assay that measures delivery to the PVC of either Kex2p or a chimeric protein (K-V), in which the Vps10p cytosolic tail replaces the Kex2p tail. Either antibody inhibition or dominant-negative Gga2p completely blocked K-V transport but only partially blocked Kex2p transport. Deletion of APL2, encoding the β subunit of AP-1, did not affect K-V transport but partially blocked Kex2p transport. Residual Kex2p transport seen with apl2Δ membranes was insensitive to dominant-negative Gga2p, suggesting that the apl2Δ mutation causes Kex2p to localize to a compartment that precludes Gga-dependent trafficking. These results suggest that yeast Ggas facilitate the specific and direct delivery of Vps10p and Kex2p from the TGN to the PVC and that AP-1 modulates Kex2p trafficking through a distinct pathway, presumably involving the early endosome.

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Soi3p/Rav1p Functions at the Early Endosome to Regulate Endocytic Trafficking to the Vacuole and Localization of Trans-Golgi Network Transmembrane Proteins

Molecular Biology of the Cell ◽

10.1091/mbc.e03-10-0755 ◽

2004 ◽

Vol 15 (7) ◽

pp. 3196-3209 ◽

Cited By ~ 27

Author(s):

György Sipos ◽

Jason H. Brickner ◽

E.J. Brace ◽

Linyi Chen ◽

Alain Rambourg ◽

...

Keyword(s):

Vacuolar Atpase ◽

Early Endosome ◽

Trans Golgi Network ◽

Peripheral Protein ◽

Early Endosomes ◽

Localization Signal ◽

Prevacuolar Compartment ◽

Gradient Fractionation ◽

Vacuolar Protein ◽

Golgi Network

SOI3 was identified by a mutation, soi3-1, that suppressed a mutant trans-Golgi network (TGN) localization signal in the Kex2p cytosolic tail. SOI3, identical to RAV1, encodes a protein important for regulated assembly of vacuolar ATPase. Here, we show that Soi3/Rav1p is required for transport between the early endosome and the late endosome/prevacuolar compartment (PVC). By electron microscopy, soi3-1 mutants massively accumulated structures that resembled early endosomes. soi3Δ mutants exhibited a kinetic delay in transfer of the endocytic tracer dye FM4-64, from the 14°C endocytic intermediate to the vacuole. The soi3Δ mutation delayed vacuolar degradation but not internalization of the a-factor receptor Ste3p. By density gradient fractionation, Soi3/Rav1p associated as a peripheral protein with membranes of a density characteristic of early endosomes. The soi3 null mutation markedly reduced the rate of Kex2p transport from the TGN to the PVC but had no effect on vacuolar protein sorting or cycling of Vps10p. These results suggest that assembly of vacuolar ATPase at the early endosome is required for transport of both Ste3p and Kex2p from the early endosome to the PVC and support a model in which cycling through the early endosome is part of the normal itinerary of Kex2p and other TGN-resident proteins.

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Faculty Opinions recommendation of Multivesicular bodies mature from the trans-Golgi network/early endosome in Arabidopsis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.13353960.14725058 ◽

2011 ◽

Author(s):

Jiri Friml ◽

Steffen Vanneste

Keyword(s):

Early Endosome ◽

Multivesicular Bodies ◽

Trans Golgi Network ◽

Golgi Network

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Trans-Golgi network/early endosome: a central sorting station for cargo proteins in plant immunity

Current Opinion in Plant Biology ◽

10.1016/j.pbi.2017.08.012 ◽

2017 ◽

Vol 40 ◽

pp. 114-121 ◽

Cited By ~ 6

Author(s):

Erica D LaMontagne ◽

Antje Heese

Keyword(s):

Plant Immunity ◽

Early Endosome ◽

Trans Golgi Network ◽

Cargo Proteins ◽

Sorting Station ◽

Golgi Network

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GLUT4 Recycles via a trans-Golgi Network (TGN) Subdomain Enriched in Syntaxins 6 and 16 But Not TGN38: Involvement of an Acidic Targeting Motif

Molecular Biology of the Cell ◽

10.1091/mbc.e02-06-0315 ◽

2003 ◽

Vol 14 (3) ◽

pp. 973-986 ◽

Cited By ~ 157

Author(s):

Annette M. Shewan ◽

Ellen M. van Dam ◽

Sally Martin ◽

Tang Bor Luen ◽

Wanjin Hong ◽

...

Keyword(s):

Cell Surface ◽

Glucose Transporter ◽

Adipocyte Differentiation ◽

Attachment Protein ◽

Trans Golgi Network ◽

Sensitive Factor ◽

Protein Receptors ◽

Glucose Transporter Glut4 ◽

Golgi Network ◽

Endosomal System

Insulin stimulates glucose transport in fat and muscle cells by triggering exocytosis of the glucose transporter GLUT4. To define the intracellular trafficking of GLUT4, we have studied the internalization of an epitope-tagged version of GLUT4 from the cell surface. GLUT4 rapidly traversed the endosomal system en route to a perinuclear location. This perinuclear GLUT4 compartment did not colocalize with endosomal markers (endosomal antigen 1 protein, transferrin) or TGN38, but showed significant overlap with the TGN target (t)-solubleN-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) Syntaxins 6 and 16. These results were confirmed by vesicle immunoisolation. Consistent with a role for Syntaxins 6 and 16 in GLUT4 trafficking we found that their expression was up-regulated significantly during adipocyte differentiation and insulin stimulated their movement to the cell surface. GLUT4 trafficking between endosomes and trans-Golgi network was regulated via an acidic targeting motif in the carboxy terminus of GLUT4, because a mutant lacking this motif was retained in endosomes. We conclude that GLUT4 is rapidly transported from the cell surface to a subdomain of thetrans-Golgi network that is enriched in the t-SNAREs Syntaxins 6 and 16 and that an acidic targeting motif in the C-terminal tail of GLUT4 plays an important role in this process.

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Dual-color visualization of trans-Golgi network to plasma membrane traffic along microtubules in living cells

Journal of Cell Science ◽

10.1242/jcs.112.1.21 ◽

1999 ◽

Vol 112 (1) ◽

pp. 21-33 ◽

Cited By ~ 17

Author(s):

D. Toomre ◽

P. Keller ◽

J. White ◽

J.C. Olivo ◽

K. Simons

Keyword(s):

Plasma Membrane ◽

Protein Trafficking ◽

Membrane Traffic ◽

Living Cells ◽

Tubular Structures ◽

Trans Golgi Network ◽

Vesicular Stomatitis ◽

Golgi Network ◽

Color Visualization

The mechanisms and carriers responsible for exocytic protein trafficking between the trans-Golgi network (TGN) and the plasma membrane remain unclear. To investigate the dynamics of TGN-to-plasma membrane traffic and role of the cytoskeleton in these processes we transfected cells with a GFP-fusion protein, vesicular stomatitis virus G protein tagged with GFP (VSVG3-GFP). After using temperature shifts to block VSVG3-GFP in the endoplasmic reticulum and subsequently accumulate it in the TGN, dynamics of TGN-to-plasma membrane transport were visualized in real time by confocal and video microscopy. Both small vesicles (<250 nm) and larger vesicular-tubular structures (>1.5 microm long) are used as transport containers (TCs). These TCs rapidly moved out of the Golgi along curvilinear paths with average speeds of approximately 0.7 micrometer/second. Automatic computer tracking objectively determined the dynamics of different carriers. Fission and fusion of TCs were observed, suggesting that these late exocytic processes are highly interactive. To directly determine the role of microtubules in post-Golgi traffic, rhodamine-tubulin was microinjected and both labeled cargo and microtubules were simultaneously visualized in living cells. These studies demonstrated that exocytic cargo moves along microtubule tracks and reveals that carriers are capable of switching between tracks.

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Immunoisolation of Kex2p-containing organelles from yeast demonstrates colocalisation of three processing proteinases to a single Golgi compartment

Journal of Cell Science ◽

10.1242/jcs.106.3.815 ◽

1993 ◽

Vol 106 (3) ◽

pp. 815-822

Author(s):

N.J. Bryant ◽

A. Boyd

Keyword(s):

Saccharomyces Cerevisiae ◽

Secretory Pathway ◽

High Yield ◽

Trans Golgi Network ◽

Processing Enzymes ◽

Terminal Domain ◽

Golgi Compartment ◽

Functional Equivalent ◽

Golgi Network

One of the Golgi compartments of Saccharomyces cerevisiae is defined by the presence of a specific endoproteinase, Kex2p, which cleaves precursor polypeptides at pairs of basic residues. We have used antibodies directed against the cytoplasmically disposed C-terminal domain of Kex2p to develop an immuno-affinity procedure for the isolation of Kex2p-containing organelles. The method gives a high yield of sealed organelles that are essentially free of contamination from other secretory pathway organelles while being significantly enriched for two other late Golgi enzymes, dipeptidylaminopeptidase A and the Kex1 carboxypeptidase. Our findings provide clear evidence for a single yeast Golgi compartment containing all three late-processing enzymes, which is likely to be the functional equivalent in yeast of the mammalian trans-Golgi network.

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