Purification and characterization from bovine brain cytosol of a protein that inhibits the dissociation of GDP from and the subsequent binding of GTP to smg p25A, a ras p21-like GTP-binding protein.

Sasaki, Takuya; Kikuchi, Akira; Araki, Shunichi; Hata, Yoshinobu; Isomura, Mitsuo; Kuroda, Shinya; Takai, Yoshimi

doi:10.1016/s0021-9258(19)39980-6

Cited by 292 publications

(54 citation statements)

References 27 publications

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“…Given that, in our permeabilised cell system, exogenously added adaptors stimulate only a limited number of steps on the pathway to coated vesicle formation, we wanted to investigate whether Rab5 was required at other stages in coated vesicle formation. Permeabilised cells were incubated with increasing amounts of GDI purified from bovine brain [30], and the extent of transferrin sequestration into deeply invaginated coated pits and its internalisation into coated vesicles was measured using the assays for avidin inaccessibility, MesNa resistance and adaptor-dependent ligand sequestration. Figure 5a-c shows that in all three assays GDI was inhibitory, with half-maximal inhibition occurring at ~0.6 µM and full inhibition occurring at 2 µM in each assay.…”

Section: Gdi Inhibits Coated Pit Assembly and Scissionmentioning

confidence: 99%

A novel role for Rab5–GDI in ligand sequestration into clathrin-coated pits

et al. 1998

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Section: Gdi Inhibits Coated Pit Assembly and Scissionmentioning

confidence: 99%

A novel role for Rab5–GDI in ligand sequestration into clathrin-coated pits

et al. 1998

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“…A model of the Rab functional mechanism has recently been proposed (2); in the cytosol, Rab proteins are found as complexes with a GDP dissociation inhibitor (GDI)1 protein (6)(7)(8)(9). Recent experiments have suggested that the GDI protein could deliver the Rab protein to a specific organelle (10,11).…”

mentioning

confidence: 99%

Two-hybrid System Screen with the Small GTP-binding Protein Rab6. IDENTIFICATION OF A NOVEL MOUSE GDP DISSOCIATION INHIBITOR ISOFORM AND TWO OTHER POTENTIAL PARTNERS OF Rab6

Janoueix‐Lerosey

Jollivet

Camonis

et al. 1995

Journal of Biological Chemistry

106

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Rab6 is a small GTP-binding protein that belongs to the Ras superfamily and is involved in intra-Golgi transport. Using a two-hybrid system screen of a mouse brain cDNA library, we have isolated several clones encoding proteins that interact with Rab6. Approximately 60% of the clones identified encoded a new mouse Rab GDP dissociation inhibitor (GDI) isoform. This GDI isoform is distinct from mouse mGDI-1 and mGDI-2, which have been characterized previously, and most likely represents the mouse counterpart of the rat Rab GDI beta isoform. In the two-hybrid system, GDI beta interacts with wild-type Rab6 and Rab5, but not with a GTP-bound Rab6 mutant, or a Rab6 mutant that cannot be post-translationally processed. We further examined whether mouse GDI beta is functional; we show that recombinant mouse GDI beta is able to remove several Rab proteins, including Rab1, Rab2, Rab4, and Rab6, from membranes. The identification of a third GDI isoform in mouse raised the question whether GDI genes belong to a larger multigenic family. We have shown, by Southern blot analysis of genomic DNA, that at least five GDI gene copies exist in both the mouse and rat genomes. In our two-hybrid screen, we have also characterized another clone that specifically interacts with Rab6. This clone was partially sequenced but shows no homology to known sequences. Finally, a third clone, interacting with both Rab5 and Rab6, also appears to encode a novel protein.

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“…Rab proteins are prenylated at their C-terminus, allowing for membrane localization (Kinsella and Maltese, 1991; Leung et al, 2006; Rossi et al, 1991; Khosravi-Far et al, 1991). Inactive Rab proteins are bound to GDP and GDP-dissociation inhibitor (GDI) and localized to the cytoplasm; upon approaching their target membrane, GDI is displaced by GDI displacement factor (GDF), allowing membrane insertion of the Rab protein (Li and Marlin, 2015; Sasaki et al, 1990; Pfeffer et al, 1995; Müller and Goody, 2018; Sivars et al, 2003). The Rab protein then interacts with a cognate guanine nucleotide exchange factor (GEF), which facilitates the replacement of GDP for GTP, activating the Rab (Blümer et al, 2013; Müller and Goody, 2018; Ullrich et al, 1994; Soldati et al, 1994; Barr and Lambright, 2010).…”

Section: Introductionmentioning

confidence: 99%

A novel function for Rab proteins during maturation of secretory granules

et al. 2021

Preprint

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Regulated exocytosis is an essential process whereby professional secretory cells synthesize and secrete specific cargo proteins in a stimulus-dependent manner. Cargo-containing secretory granules are synthesized in the trans-Golgi Network (TGN); after budding from the TGN, granules undergo many modifications, including a dramatic increase in size. These changes occur during a poorly understood process called secretory granule maturation. Here we leverage the professional secretory cells of the Drosophila larval salivary glands as a model system to characterize a novel and unexpected role for Rab GTPases during secretory granule maturation. We find that secretory granules in the larval salivary glands increase in size ~300-fold between biogenesis and release, and loss of Rab1 or Rab11 dramatically reduces granule size. Surprisingly, we find that Rab1 and Rab11 protein localize to secretory granule membranes. Rab11 associates with granule membranes throughout the maturation process, and Rab11 is required for recruitment of Rab1. In turn, Rab1 associates specifically with immature secretory granules and drives granule growth. In addition to their roles in granule growth, both Rab1 and Rab11 appear to have additional roles during exocytosis; Rab11 function is necessary for exocytosis, while the presence of Rab1 on immature granules may prevent precocious exocytosis. Overall, these results highlight a new and unexpected role for Rab GTPases in secretory granule maturation.

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Purification and characterization from bovine brain cytosol of a protein that inhibits the dissociation of GDP from and the subsequent binding of GTP to smg p25A, a ras p21-like GTP-binding protein.

Cited by 292 publications

References 27 publications

A novel role for Rab5–GDI in ligand sequestration into clathrin-coated pits

A novel role for Rab5–GDI in ligand sequestration into clathrin-coated pits

Two-hybrid System Screen with the Small GTP-binding Protein Rab6. IDENTIFICATION OF A NOVEL MOUSE GDP DISSOCIATION INHIBITOR ISOFORM AND TWO OTHER POTENTIAL PARTNERS OF Rab6

A novel function for Rab proteins during maturation of secretory granules

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