The small GTP-binding protein rab6 functions in intra-Golgi transport (original) (raw)
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The Journal of Cell Biology, 1992
We have examined the role of ms-related rab proteins in transport from the ER to the Golgi complex in vivo using a vaccinia recombinant T7 RNA polymerase virus to express site-directed rab mutants. These mutations are within highly conserved domains involved in guanine nucleotide binding and hydrolysis found in ras and all members of the ras superfamily. Substitutions in the GTP-binding domains of rabla and rablb (equivalent to the ras 17N and 116I mutants) resulted in proteins which were potent trans dominant inhibitors of vesicular stomatitis virus glycoprotein (VSV-G protein) transport between the ER and cis Golgi complex. Immunofluorescence analysis indicated that expression of rablbl:u prevented delivery 1. Abbreviations used in this paper: GAP, GTPase activating protein; GDI, guanine nucleotide dissociation inhibitor; GDS, guanine nucleotide dissociation stimulator; NGS, normal goat serum; VSG-V, vesicular stornatitis virus glycoprotein.
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.
FEBS Letters, 2012
Inclusion of proteins into membrane-rafts favours interactions required for virus assembly but has also been proposed to facilitate vesicular transport of proteins. The hemagglutinin (HA) of influenza virus contains a raft-targeting sequence in the outer leaflet of its transmembrane region. We report that its mutation enhances co-localization of HA with a cis-Golgi marker and retards Golgi-localized processing, such as acquisition of Endo-H resistant carbohydrates and proteolytic cleavage. In contrast, trimerization of the molecule in the ER and transport to the apical membrane were not affected. The second signal for raft-targeting, S-acylation at cytoplasmic cysteines, did not retard HA transport.
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.
Traffic, 2002
Golgi network that interacts with microtubule minus ends. GMAP-210 overexpression has previously been shown to perturb the microtubule network and to induce a dramatic enlargement and fragmentation of the Golgi apparatus (Infante C, Ramos-Morales F, Fedriani C, Bornens M, Rios RM. J Cell Biol 1999; 145: 83-98). We now report that overexpressing GMAP-210 blocks the anterograde transport of both a soluble form of alkaline phosphatase and the hemagglutinin protein of influenza virus, an integral membrane protein, between the endoplasmic reticulum and the cis/medial (mannosidase II-positive) Golgi compartment. Retrograde transport of the Shiga toxin B-subunit is also blocked between the Golgi apparatus and the endoplasmic reticulum. As a consequence, the B-subunit accumulates in compartments positive for GMAP-210. Ultrastructural analysis revealed that, under these conditions, the Golgi complex is totally disassembled and Golgi proteins as well as proteins of the intermediate compartment are found in vesicle clusters distributed throughout the cell. The role of GMAP-210 on membrane processes at the interface between the endoplasmic reticulum and the Golgi apparatus is discussed in the light of the property of this protein to bind CGN membranes and microtubules.
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.
The EMBO journal, 1986
Mutants ts1 and ts227 of fowl plague virus have a temperature-sensitive defect in the transport of the hemagglutinin from the rough endoplasmic reticulum to the Golgi apparatus. The primary structure of the hemagglutinin of the mutants and of a number of revertants derived from them has been analysed by nucleotide sequencing. The transport block of the hemagglutinin of ts227 can be attributed to a single amino acid exchange. It involves the replacement of aspartic acid at position 457 by asparagine thereby introducing a new glycosylation site which appears to be located in a cryptic position in the lower part of the hemagglutinin stalk. Attachment of carbohydrate to this site is temperature-dependent. At permissive temperature only a small fraction of the monomers (approximately 30%) is glycosylated in this position, whereas at nonpermissive temperature this is the case with all subunits. The data suggest that under the latter conditions the new oligosaccharide interferes by steric ...