Involvement of GTP-binding “G” proteins in transport through the Golgi stack

Melançon, Paul; Glick, Benjamin S.; Malhotra, Vivek; Weidman, P J; Serafini, Tito; Gleason, Michael L.; Orci, Lelio; Rothman, James E.

doi:10.1016/0092-8674(87)90591-5

Cited by 497 publications

(258 citation statements)

References 21 publications

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“…This extends the biochemical observations of Taylor and Melançon (53), who used a less selective method for ARF-depletion and found that in vitro transport in the medial assay was still inhibited by AlF (53). These results are also consistent with the finding that cholera and pertussis toxin-dependent ADPribosylation of G s or G i/o has no effect on cell-free Golgi transport (17,54), and that peptide activators of trimeric Gproteins inhibit transport only at concentrations that damage membranes (26). Thus, it would appear that the AlF-sensitive component in the in vitro transport assay is not a trimeric G protein, and may not even be a GTP-binding protein.…”

Section: G Proteins and The Inhibition Of Golgi Transport By Alfsupporting

confidence: 87%

Coatomer Vesicles are not Required for Inhibition of Golgi Transport by G‐Protein Activators

Happe

Cairns

Roth

et al. 2000

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The G-protein activators guanosine 5%-O-(3-thiodiphosphate) (GTPgS) and aluminum fluoride (AlF) are thought to inhibit transport between Golgi cisternae by causing the accumulation of nonfunctional coatomer-coated transport vesicles on the Golgi. Although GTPgS and AlF inhibit transport in cell-free intra-Golgi transport systems, blocking coatomer vesicle formation does not. We therefore determined whether inhibition of in vitro Golgi transport by these agents requires coatomer vesicle formation. Depletion of coatomer was found to completely block coated vesicle formation on Golgi cisternae without affecting inhibition of in vitro transport by either GTPgS or AlF. Depletion of ADP-ribosylation factor (ARF) prevented inhibition of transport by GTPgS, but not by AlF, suggesting that the AlF-sensitive component in transport may not be a GTP-binding protein. Surprisingly, depletion of cytosolic ARF did not prevent the GTPgS-induced formation of Golgi-coated vesicles, whereas ARF was required for AlF-induced vesicle formation. Although ARF or coatomer depletion caused an increase in the fenestration of cisternae, no other utrastructural changes were observed that might explain the inhibition of transport by GTPgS or AlF. These findings suggest that ARF-GTPgS and AlF act by distinct and coatomer-independent mechanisms to inhibit membrane fusion in cell-free intra-Golgi transport.

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Section: G Proteins and The Inhibition Of Golgi Transport By Alfsupporting

confidence: 87%

Coatomer Vesicles are not Required for Inhibition of Golgi Transport by G‐Protein Activators

Happe

Cairns

Roth

et al. 2000

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“…Often this will antagonize the activation of a G protein, and this is usually interpreted as being due to the fly complexing with and inactivating the a subunit (Northup et al, 1983). However, it can be very difficult to sort another function(s) is the finding that there are intracellular pools of heterotrimeric G proteins, both bound to internal membranes (Codina et al, 1988;Ali et al, 1989), and for Gsa, also free in the cytoplasm (Ransnas et al, 1989;Negishi et al, 1992;Bomsel and Mostov, unpublished data The original indication that G proteins are involved in membrane traffic was the finding several years ago (Melancon et al, 1987;Taylor et al, 1992).…”

mentioning

confidence: 99%

“…that GTPyS (a nonhydrolyzable analogue of GTP) and complexes of aluminum and fluoride (probably AlF4-), which bind to the GDP-bound form of some GTPbinding proteins and mimic the y phosphate of GTP (reviewed in Chabre, 1990), inhibited various steps in the secretory (Melancon et al, 1987) and endocytotic pathways (Mayorga et al, 1989). It was not clear at the time if these agents were acting on monomeric GTPbinding proteins and/or heterotrimeric G proteins.…”

mentioning

confidence: 99%

Role of heterotrimeric G proteins in membrane traffic.

Bomsel

Mostov

1992

MBoC

207

142

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“…This might indicate that 7B2 represents a member of a novel family of lowmolecular mass, secretory granule-associated GTP-binding proteins. Interestingly, recent evidence suggests that GTP-binding proteins participate in translocation of proteins across the endoplasmic reticulum [22], intercisternal protein transport within the Golgi stack [23] and fusion of secretory granule and plasma membranes during triggered exocytotic secretion [24]. Our cloning of the 7B2 cDNA provides tools to study whether the 7B2 protein is a GTP-binding protein involved in the pathway of protein secretion.…”

Section: Discussionmentioning

confidence: 99%

Cloning and sequence analysis of human pituitary cDNA encoding the novel polypeptide 7B2

Martens

1988

FEBS Letters

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Applicationof a differential hybridization technique led to the isolation of a human pituitary cDNA clone encoding the complete structure of the polypeptide 7B2. This protein of unknown function, which is sorted to secretory granules, appears to be present selectively in neurons and endocrine cells. The polypeptide chain of human 7B2, preceded by a cleaved signal peptide, comprises I85 amino acids (a calculated M, of 20793). Interesting features of the highly-conserved 7B2 structure include (i) a serine phosphorylation consensus sequence, (ii) the occurrence of three pairs of dibasic amino acids representing potential proteolytic cleavage sites and, in particular, (iii) the presence of three regions homologous to GTPbinding domains giving 7B2 structural characteristics of a GTP-binding protein.

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Involvement of GTP-binding “G” proteins in transport through the Golgi stack

Cited by 497 publications

References 21 publications

Coatomer Vesicles are not Required for Inhibition of Golgi Transport by G‐Protein Activators

Coatomer Vesicles are not Required for Inhibition of Golgi Transport by G‐Protein Activators

Role of heterotrimeric G proteins in membrane traffic.

Cloning and sequence analysis of human pituitary cDNA encoding the novel polypeptide 7B2

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