Rab18 and Rab43 have key roles in ER-Golgi trafficking (original) (raw)
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Rab proteins as major determinants of the Golgi complex structure
Small GTPases, 2017
GTP-ases of the Rab family (about 70 in human) are key regulators of intracellular transport and membrane trafficking in eukaryotic cells. Remarkably, almost one third associate with membranes of the Golgi complex and TGN (trans-Golgi network). Through interactions with a variety of effectors that include molecular motors, tethering complexes, scaffolding proteins and lipid kinases, they play an important role in maintaining Golgi architecture.
Rab22B’s role in trans-Golgi network membrane dynamics
Biochemical and Biophysical Research Communications, 2007
The small GTPase Rab22B (or Rab31) has been suspected to be involved in trafficking at trans-Golgi network. However, its exact cellular localization, tissue expression profile, and functions have not been uncharacterized. Specific antibody raised against Rab22B's protein revealed that Rab22B is brain-enriched, but is also present in substantial levels in spleen and intestine. In HeLa cells, endogenous Rab22B is largely associated with the trans-Golgi network (TGN). Over-expression of a GDP-binding mutant (Rab22BSN), but not wild-type Rab22B, specifically disrupts the TGN localization of TGN46, a dynamic marker which cycles between the TGN and the plasma membrane. The TGN resident membrane protein syntaxin 16, cis-Golgi markers such as GM130 and syntaxin 5, as well as the TGN/late endosome marker mannose 6-phosphate receptor (M6PR) are not affected by Rab22BSN, neither was endosomal-TGN transport of the Shiga toxin B subunit. The disruption of TGN46 staining by Rab22BSN could be specifically attributed to a domain at the C-terminal portion of Rab22B, where its sequence deviates the most from Rab22A. Over-expression of Rab22BSN inhibits the cell surface transport of the vesicular stomatitis virus G protein. Thus, Rab22B may have a role in anterograde exit from the TGN.
Journal of Cell Biology, 2004
Rud3p is a coiled-coil protein of the yeast cis-Golgi. We find that Rud3p is localized to the Golgi via a COOH-terminal domain that is distantly related to the GRIP domain that recruits several coiled-coil proteins to the trans-Golgi by binding the small Arf-like GTPase Arl1p. In contrast, Rud3p binds to the GTPase Arf1p via this COOH-terminal “GRIP-related Arf-binding” (GRAB) domain. Deletion of RUD3 is lethal in the absence of the Golgi GTPase Ypt6p, and a screen of other mutants showing a similar genetic interaction revealed that Golgi targeting of Rud3p also requires Erv14p, a cargo receptor that cycles between the endoplasmic reticulum and Golgi. The one human protein with a GRAB domain, GMAP-210 (CEV14/Trip11/Trip230), is known to be on the cis-Golgi, but the COOH-terminal region that contains the GRAB domain has been reported to bind to centrosomes and γ-tubulin (Rios, R.M, A. Sanchis, A.M. Tassin, C. Fedriani, and M. Bornens. 2004. Cell. 118:323–335). In contrast, we find th...
Rab and Arl GTPase Family Members Cooperate in the Localization of the Golgin GCC185
Cell, 2008
GCC185 is a large coiled-coil protein at the trans Golgi network that is required for receipt of transport vesicles inbound from late endosomes and for anchoring noncentrosomal microtubules that emanate from the Golgi. Here, we demonstrate that recruitment of GCC185 to the Golgi is mediated by two Golgi-localized small GTPases of the Rab and Arl families. GCC185 binds Rab6, and mutation of residues needed for Rab binding abolishes Golgi localization. The crystal structure of Rab6 bound to the GCC185 Rab-binding domain reveals that Rab6 recognizes a twofold symmetric surface on a coiled coil immediately adjacent to a C-terminal GRIP domain. Unexpectedly, Rab6 binding promotes association of Arl1 with the GRIP domain. We present a structure-derived model for dual GTPase membrane attachment that highlights the potential ability of Rab GTPases to reach binding partners at a significant distance from the membrane via their unstructured and membrane-anchored, hypervariable domains.
2007
We used multiple approaches to investigate the role of Rab6 relative to Zeste White 10 (ZW10), a mitotic checkpoint protein implicated in Golgi/endoplasmic reticulum (ER) trafficking/transport, and conserved oligomeric Golgi (COG) complex, a putative tether in retrograde, intra-Golgi trafficking. ZW10 depletion resulted in a central, disconnected cluster of Golgi elements and inhibition of ERGIC53 and Golgi enzyme recycling to ER. Small interfering RNA (siRNA) against RINT-1, a protein linker between ZW10 and the ER soluble N-ethylmaleimide-sensitive factor attachment protein receptor, syntaxin 18, produced similar Golgi disruption. COG3 depletion fragmented the Golgi and produced vesicles; vesicle formation was unaffected by codepletion of ZW10 along with COG, suggesting ZW10 and COG act separately.
Rab6 Coordinates a Novel Golgi to ER Retrograde Transport Pathway in Live Cells
The Journal of Cell Biology, 1999
We visualized a fluorescent-protein (FP) fusion to Rab6, a Golgi-associated GTPase, in conjunction with fluorescent secretory pathway markers. FP-Rab6 defined highly dynamic transport carriers (TCs) translocating from the Golgi to the cell periphery. FP-Rab6 TCs specifically accumulated a retrograde cargo, the wild-type Shiga toxin B-fragment (STB), during STB transport from the Golgi to the endoplasmic reticulum (ER). FP-Rab6 TCs associated intimately with the ER, and STB entered the ER via specialized peripheral regions that accumulated FP-Rab6. Microinjection of antibodies that block coatomer protein I (COPI) function inhibited trafficking of a KDEL-receptor FP-fusion, but not FP-Rab6. Additionally, markers of COPI-dependent recycling were excluded from FP-Rab6/STB TCs. Overexpression of Rab6:GDP (T27N mutant) using T7 vaccinia inhibited toxicity of Shiga holotoxin, but did not alter STB transport to the Golgi or Golgi morphology. Taken together, our results indicate Rab6 regulates a novel Golgi to ER transport pathway.
Disruption of Golgi morphology and trafficking in cells expressing mutant prenylated rab acceptor-1
Journal of Biological …, 2002
Prenylated Rab acceptor (PRA1) is a protein that binds Rab GTPases and the v-SNARE VAMP2. The protein is localized to the Golgi complex and post-Golgi vesicles. To determine its functional role, we generated a number of point mutations and divided them into three classes based on cellular localization. Class A mutants were retained in the endoplasmic reticulum (ER) and exerted an inhibitory effect on transport of vesicular stomatitis virus envelope glycoprotein (VSVG) from the ER to Golgi as well as to the plasma membrane. Class B mutants exhibited a highly condensed Golgi complex and inhibited exit of anterograde cargo from this organelle. Class C mutants exhibited an intermediate phenotype with Golgi and ER localization along with extensive tubular structures emanating from the Golgi complex. There was a direct correlation between the cellular phenotype and binding to Rab and VAMP2. Class A and C mutants showed a significant decrease in Rab and VAMP2 binding, whereas an increase in binding was observed in the class B mutants. Thus, PRA1 is required for vesicle formation from the Golgi complex and might be involved in recruitment of Rab effectors and SNARE proteins during cargo sequestration.
GTP-bound forms of rab6 induce the redistribution of Golgi proteins into the endoplasmic reticulum
Proceedings of the National Academy of Sciences, 1997
rab6 is a ubiquitous ras-like GTPase involved in intra-Golgi transport. We have studied at both morphological and biochemical levels the behavior of Golgi resident proteins in HeLa cells overexpressing wild-type rab6 and GTP-and GDP-bound mutants of rab6 (rab6 Q72L and rab6 T27N, respectively). We show that wild-type rab6 and rab6 Q72L overexpression induces the redistribution of the trans-Golgi protein -1,4-galactosyltransferase into the endoplasmic reticulum (ER) and allows the addition of sialylated O-glycans on an ER-retained protein, the major histocompatibility complex class II-associated invariant chain. Remarkably, rab6 Q72L effects, which require the integrity of microtubules, were almost indistinguishable from those induced by brefeldin A, a fungic metabolite that causes a mixing of Golgi and ER membranes. In contrast, overexpression of rab6 T27N does not cause the redistribution of Golgi proteins, but inhibits basal O-glycosylation of the major histocompatibility complex class II-associated invariant chain.
Golgi-bound Rab34 Is a Novel Member of the Secretory Pathway
Molecular Biology of the Cell, 2007
Golgi-localized Rab34 has been implicated in repositioning lysosomes and activation of macropinocytosis. Using HeLa cells, we undertook a detailed investigation of Rab34 involvement in intracellular vesicle transport. Immunoelectron microscopy and immunocytochemistry confirmed that Rab34 is localized to the Golgi stack and that active Rab34 shifts lysosomes to the cell center. Contrary to a previous report, we found that Rab34 is not concentrated at membrane ruffles and is not involved in fluid-phase uptake. Also, Rab34-induced repositioning of lysosomes does not affect mannose 6-phosphate receptor trafficking. Most strikingly, HeLa cells depleted of Rab34 by transfection with dominant-negative Rab34 or after RNA interference, failed to transport the temperature-sensitive vesicular stomatitis virus G-protein (VSVG) fused to green fluorescent protein (VSVG-GFP) from the Golgi to the plasma membrane. Transfection with mouse Rab34 rescued this defect. Using endogenous major histocompat...