Multiple GTP-binding proteins regulate vesicular transport from the ER to Golgi membranes.

Schwaninger, Ruth; Plutner, Helen; Bokoch, Gary M.; Balch, William E.

doi:10.1083/jcb.119.5.1077

Cited by 118 publications

(70 citation statements)

References 103 publications

(171 reference statements)

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“…2E and F), which is an ER luminal protein (35,44), nor with Rab1B (data not shown), which localizes to the cytoplasmic surface of the ER/cis-Golgi intermediate compartment and/or cis-Golgi (25,52,58). In contrast, 85YG p17 (MA) staining substantially colocalized with the region stained by fluorosceinlabeled RCA60 (Fig.…”

Section: Resultsmentioning

confidence: 84%

Role of the Gag Matrix Domain in Targeting Human Immunodeficiency Virus Type 1 Assembly

Ono

Orenstein

Freed

2000

J Virol

222

236

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Human immunodeficiency virus type 1 (HIV-1) particle formation and the subsequent initiation of proteasemediated maturation occur predominantly on the plasma membrane. However, the mechanism by which HIV-1 assembly is targeted specifically to the plasma membrane versus intracellular membranes is largely unknown. Previously, we observed that mutations between residues 84 and 88 of the matrix (MA) domain of HIV-1 Gag cause a retargeting of virus particle formation to an intracellular site. In this study, we demonstrate that the mutant virus assembly occurs in the Golgi or in post-Golgi vesicles. These particles undergo core condensation in a protease-dependent manner, indicating that virus maturation can occur not only on the plasma membrane but also in the Golgi or post-Golgi vesicles. The intracellular assembly of mutant particles is dependent on Gag myristylation but is not influenced by p6Gag or envelope glycoprotein expression. Previous characterization of viral revertants suggested a functional relationship between the highly basic domain of MA (amino acids 17 to 31) and residues 84 to 88. We now demonstrate that mutations in the highly basic domain also retarget virus particle formation to the Golgi or post-Golgi vesicles. Although the basic domain has been implicated in Gag membrane binding, no correlation was observed between the impact of mutations on membrane binding and Gag targeting, indicating that these two functions of MA are genetically separable. Plasma membrane targeting of Gag proteins with mutations in either the basic domain or between residues 84 and 88 was rescued by coexpression with wild-type Gag; however, the two groups of MA mutants could not rescue each other. We propose that the highly basic domain of MA contains a major determinant of HIV-1 Gag plasma membrane targeting and that mutations between residues 84 and 88 disrupt plasma membrane targeting through an effect on the basic domain.

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Section: Resultsmentioning

confidence: 84%

Role of the Gag Matrix Domain in Targeting Human Immunodeficiency Virus Type 1 Assembly

Ono

Orenstein

Freed

2000

J Virol

222

236

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“…However, in permeabilized NRK cells neither pertussis toxin nor cholera toxin (which constitutively activates Gets) had an effect on 13~/-induced inhibition of VSV-G export from the ER (50). Thus, the available data do not point to a general mechanism by which Get proteins regulate transport, but rather suggest there may be cell type-and compartment-specific variations.…”

mentioning

confidence: 66%

Differential distribution of alpha subunits and beta gamma subunits of heterotrimeric G proteins on Golgi membranes of the exocrine pancreas.

Denker

McCaffery

Palade

et al. 1996

The Journal of Cell Biology

129

100

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Abstract. Heterotrimeric G proteins are well known to be involved in signaling via plasma membrane (PM) receptors. Recent data indicate that heterotrimeric G proteins are also present on intracellular membranes and may regulate vesicular transport along the exocytic pathway. We have used subcellular ffactionation and immunocytochemical localization to investigate the distribution of Get and Gi3~/subunits in the rat exocrine pancreas which is highly specialized for protein secretion. We show that Gas, Goti3 and Gotq/11 are present in Golgi fractions which are >95% devoid of PM. Removal of residual PM by absorption on wheat germ agglutinin (WGA) did not deplete Got subunits. Gots was largely restricted to TGN-enriched fractions by immunoblotting, whereas Goti3 and Gotq/n were broadly distributed across Golgi fractions. Gets did not colocalize with TGN38 or caveolin, suggesting that Gets is associated with a distinct population of membranes. G[3 subunits were barely detectable in purified Golgi fractions.

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“…8B). Colocalization of these proteins with Rab1B, which locates to the ER/cis-Golgi intermediate compartment or to the cis-Golgi (28,54), was also performed. Although some of the green and red fluorescence images appeared to be slightly superimposed (Fig.…”

Section: Vol 75 2001 Membrane Interaction and Hiv-1 Infectivity 993mentioning

confidence: 99%

Cellular Membrane-Binding Ability of the C-Terminal Cytoplasmic Domain of Human Immunodeficiency Virus Type 1 Envelope Transmembrane Protein gp41

Chen

Lee

Wang

2001

J Virol

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The amphipathic ␣-helices located in the cytoplasmic tail of the envelope (Env) transmembrane glycoprotein gp41 of human immunodeficiency virus type 1 have been implicated in membrane association and cytopathicity. Deletion of the last 12 amino acids in the C terminus of this domain severely impairs infectivity. However, the nature of the involvement of the cytoplasmic tail in Env-membrane interactions in cells and the molecular basis for the defect in infectivity of this mutant virus are still poorly understood. In this study we examined the interaction of the cytoplasmic tail with membranes in living mammalian cells by expressing a recombinant cytoplasmic tail fragment and an Escherichia coli ␤-galactosidase/cytoplasmic tail fusion protein, both of them lacking gp120, the gp41 ectodomain, and the transmembrane region. We found through cell fractionation, in vivo membrane flotation, and confocal immunofluorescence studies that the cytoplasmic tail contained determinants to be routed to a perinuclear membrane region in cells. Further mapping showed that each of the three lentivirus lytic peptide (LLP-1, LLP-2, and LLP-3) sequences conferred this cellular membrane-targeting ability. Deletion of the last 12 amino acids from the C terminus abolished the ability of the LLP-1 motif to bind to membranes. High salt extraction, in vitro transcription and translation, and posttranslational membrane binding analyses indicated that the ␤-galactosidase/LLP fusion proteins were inserted into membranes via the LLP sequences. Subcellular fractionation and confocal microscopy studies revealed that each of the LLP motifs, acting in a position-independent manner, targeted non-endoplasmic reticulum (ER)-associated ␤-galactosidase and enhanced green fluorescence protein to the ER. Our study provides a basis for the involvement of the gp41 cytoplasmic tail during Env maturation and also supports the notion that the membrane apposition of the C-terminal cytoplasmic tail plays a crucial role in virus-host interaction.The cytoplasmic domain of human immunodeficiency virus type 1 (HIV-1) envelope (Env) transmembrane (TM) glycoprotein gp41 has multiple functions in the virus life cycle. Mutations, deletions, and truncations in this region may affect virus replication, infectivity, cytopathicity, Env incorporation into virions, cell type-dependent Env stability, and interaction with the viral matrix (MA) protein. A deletion of 144 amino acids, which comprise most of the cytoplasmic tail, from the C terminus of gp41 does not affect virus infectivity, Env assembly into virions, and cytopathogenicity in MT-4 cells (66). The differential virus infectivity of this mutant in permissive cells (MT-4 and M8166) and nonpermissive cells (most T-cell lines and primary cells) can be attributed to the differential requirement of the cytoplasmic tail to incorporate gp120 into virions in different cell types (1, 46). We previously reported that an Env mutant of HIV-1 lacking the whole cytoplasmic tail and the last two amino acids in the TM region can tra...

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Multiple GTP-binding proteins regulate vesicular transport from the ER to Golgi membranes.

Abstract: Abstract. Using indirect immunofluorescence we have examined the effects of reagents which inhibit the function of ras-related rab small GTP-binding proteins and heterotrimeric G~ proteins in ER to Golgi transport.

Cited by 118 publications

References 103 publications

Role of the Gag Matrix Domain in Targeting Human Immunodeficiency Virus Type 1 Assembly

Role of the Gag Matrix Domain in Targeting Human Immunodeficiency Virus Type 1 Assembly

Differential distribution of alpha subunits and beta gamma subunits of heterotrimeric G proteins on Golgi membranes of the exocrine pancreas.

Cellular Membrane-Binding Ability of the C-Terminal Cytoplasmic Domain of Human Immunodeficiency Virus Type 1 Envelope Transmembrane Protein gp41

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