scholarly journals A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein.

1991 ◽  
Vol 11 (5) ◽  
pp. 2909-2912 ◽  
Author(s):  
T Sasaki ◽  
K Kaibuchi ◽  
A K Kabcenell ◽  
P J Novick ◽  
Y Takai
Keyword(s):  
Exchange Reaction ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Yeast Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Constitutive Secretion ◽  
Gdp Dissociation Inhibitor ◽  
Exchange Protein

Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.

A mammalian inhibitory GDP/GTP exchange protein (GDP dissociation inhibitor) for smg p25A is active on the yeast SEC4 protein

1991 ◽  
Vol 11 (5) ◽  
pp. 2909-2912
Author(s):  
T Sasaki ◽  
K Kaibuchi ◽  
A K Kabcenell ◽  
P J Novick ◽  
Y Takai
Keyword(s):  
Exchange Reaction ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Yeast Cells ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Constitutive Secretion ◽  
Gdp Dissociation Inhibitor ◽  
Exchange Protein

Evidence is accumulating that smg p25A, a small GTP-binding protein, may be involved in the regulated secretory processes of mammalian cells. The SEC4 protein is known to be required for constitutive secretion in yeast cells. We show here that the mammalian GDP dissociation inhibitor (GDI), which was identified by its action on smg p25A, is active on the yeast SEC4 protein in inhibiting the GDP/GTP exchange reaction and is capable of forming a complex with the GDP-bound form of the SEC4 protein but not with the GTP-bound form. These results together with our previous findings that smg p25A GDI is found in mammalian cells with both regulated and constitutive secretion types suggest that smg p25A GDI plays a role in both regulated and constitutive secretory processes, although smg p25A itself may be involved only in regulated secretory processes. These results also suggest that a GDI for the SEC4 protein is present in yeast cells.

scholarly journals Rab1b regulates vesicular transport between the endoplasmic reticulum and successive Golgi compartments.

1991 ◽  
Vol 115 (1) ◽  
pp. 31-43 ◽  
Author(s):  
H Plutner ◽  
A D Cox ◽  
S Pind ◽  
R Khosravi-Far ◽  
J R Bourne ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Essential Role ◽  
Secretory Pathway ◽  
Binding Protein ◽  
Vesicular Transport ◽  
Initial Step ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Golgi Compartment

We report an essential role for the ras-related small GTP-binding protein rab1b in vesicular transport in mammalian cells. mAbs detect rab1b in both the ER and Golgi compartments. Using an assay which reconstitutes transport between the ER and the cis-Golgi compartment, we find that rab1b is required during an initial step in export of protein from the ER. In addition, it is also required for transport of protein between successive cis- and medial-Golgi compartments. We suggest that rab1b may provide a common link between upstream and downstream components of the vesicular fission and fusion machinery functioning in early compartments of the secretory pathway.

The small GTP-binding protein Rho regulates a phosphatidylinositol 4-phosphate 5-kinase in mammalian cells

Cell ◽  
1994 ◽  
Vol 79 (3) ◽  
pp. 507-513 ◽  
Author(s):  
Lisa D. Chong ◽  
Alexis Traynor-Kaplan ◽  
Gary M. Bokoch ◽  
Martin Alexander Schwartz
Keyword(s):  
Mammalian Cells ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Phosphatidylinositol 4

Molecular cloning and characterization of a novel type of regulatory protein (GDI) for smg p25A, a ras p21-like GTP-binding protein

1990 ◽  
Vol 10 (8) ◽  
pp. 4116-4122
Author(s):  
Y Matsui ◽  
A Kikuchi ◽  
S Araki ◽  
Y Hata ◽  
J Kondo ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Exchange Reaction ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Bovine Brain ◽  
Subunit Structure ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Ras P21

We recently purified to near homogeneity a novel type of regulatory protein for smg p25A, a ras p21-like GTP-binding protein, from bovine brain cytosol. This regulatory protein, named smg p25A GDP dissociation inhibitor (GDI), regulates the GDP-GTP exchange reaction of smg p25A by inhibiting dissociation of GDP from and subsequent binding of GTP to it. In the present studies, we isolated and sequenced the cDNA of smg p25A GDI from a bovine brain cDNA library by using an oligonucleotide probe designed from the partial amino acid sequence of purified smg p25A GDI. The cDNA has an open reading frame that encodes a protein of 447 amino acids with a calculated Mr of 50,565. This Mr is similar to those of the purified smg p25A GDI estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose density gradient ultracentrifugation, which are about 54,000 and 65,000, respectively. The isolated cDNA is expressed in Escherichia coli, and the encoded protein exhibits GDI activity. smg p25A GDI is hydrophilic overall, except for one hydrophobic region near the N terminus. smg p25A GDI shares low amino acid sequence homology with the Saccharomyces cerevisiae CDC25-encoded protein, which has been suggested to serve as a factor that regulates the GDP-GTP exchange reaction of the yeast RAS2-encoded protein, but not with the beta gamma subunits of GTP-binding proteins having an alpha beta gamma subunit structure, such as Gs and Gi. The smg p25A GDI mRNA was present in various tissues, including not only tissues in which smg p25A was detectable but also tissues in which it was not detectable. This fact has raised the possibility that smg p25A GDI interacts with another G protein in tissues in which smg p25A is absent.

scholarly journals Molecular cloning and characterization of a novel type of regulatory protein (GDI) for smg p25A, a ras p21-like GTP-binding protein.

1990 ◽  
Vol 10 (8) ◽  
pp. 4116-4122 ◽  
Author(s):  
Y Matsui ◽  
A Kikuchi ◽  
S Araki ◽  
Y Hata ◽  
J Kondo ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Exchange Reaction ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Bovine Brain ◽  
Subunit Structure ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Ras P21

We recently purified to near homogeneity a novel type of regulatory protein for smg p25A, a ras p21-like GTP-binding protein, from bovine brain cytosol. This regulatory protein, named smg p25A GDP dissociation inhibitor (GDI), regulates the GDP-GTP exchange reaction of smg p25A by inhibiting dissociation of GDP from and subsequent binding of GTP to it. In the present studies, we isolated and sequenced the cDNA of smg p25A GDI from a bovine brain cDNA library by using an oligonucleotide probe designed from the partial amino acid sequence of purified smg p25A GDI. The cDNA has an open reading frame that encodes a protein of 447 amino acids with a calculated Mr of 50,565. This Mr is similar to those of the purified smg p25A GDI estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and sucrose density gradient ultracentrifugation, which are about 54,000 and 65,000, respectively. The isolated cDNA is expressed in Escherichia coli, and the encoded protein exhibits GDI activity. smg p25A GDI is hydrophilic overall, except for one hydrophobic region near the N terminus. smg p25A GDI shares low amino acid sequence homology with the Saccharomyces cerevisiae CDC25-encoded protein, which has been suggested to serve as a factor that regulates the GDP-GTP exchange reaction of the yeast RAS2-encoded protein, but not with the beta gamma subunits of GTP-binding proteins having an alpha beta gamma subunit structure, such as Gs and Gi. The smg p25A GDI mRNA was present in various tissues, including not only tissues in which smg p25A was detectable but also tissues in which it was not detectable. This fact has raised the possibility that smg p25A GDI interacts with another G protein in tissues in which smg p25A is absent.

GDP/GTP exchange reaction-stimulating activity of Rabphilin-3A for Rab 3A small GTP-binding protein

FEBS Letters ◽  
1994 ◽  
Vol 353 (1) ◽  
pp. 67-70 ◽  
Author(s):  
Yasuyuki Fujita ◽  
Takuya Sasaki ◽  
Keishi Araki ◽  
Kazuo Takahashi ◽  
Katsunori Imazumi ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Binding Protein ◽  
Gtp Binding Protein ◽  
Gtp Binding

scholarly journals rho, a Small GTP-Binding Protein, Is Essential for Shigella Invasion of Epithelial Cells

1997 ◽  
Vol 185 (2) ◽  
pp. 281-292 ◽  
Author(s):  
Masahisa Watarai ◽  
Yoichi Kamata ◽  
Shunji Kozaki ◽  
Chihiro Sasakawa
Keyword(s):  
Epithelial Cells ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Binding Protein ◽  
Shigella Flexneri ◽  
Chinese Hamster ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Causative Agents ◽  
Invasive Capacity

Shigella, the causative agents of bacillary dysentery, are capable of invading mammalian cells that are not normally phagocytic. Uptake of bacteria by the mammalian cells is directed by bacterial factors named IpaB, IpaC, and IpaD invasins, in which Ipa invasins secreted into the bacterial environment can interact with α5β1 integrin. We report here that Shigella invasion of epithelial cells requires rho activity, a ras-related GTP-binding protein. The invasive capacity of Shigella flexneri for Chinese hamster ovary (CHO) cells and other epithelial cells were greatly reduced when treated with Clostridium botulinum exoenzyme C3 transferase. Conversely, uptake of bacteria by CHO cells was promoted upon microinjection of an activated rho variant, Val14RhoA. Attachment of S. flexneri to CHO cells can elicit tyrosine phosphorylation of pp125FAK and paxillin, localized accumulation of F-actin, vinculin, and talin, and activation of protein kinase C, which were all blocked by the treatment with C3 transferase. Our results indicate that cellular signal transduction regulated by rho is essential for Shigella invasion of epithelial cells.

scholarly journals A human homologue of the yeast GST1 gene codes for a GTP-binding protein and is expressed in a proliferation-dependent manner in mammalian cells.

1989 ◽  
Vol 8 (12) ◽  
pp. 3807-3814 ◽  
Author(s):  
S. Hoshino ◽  
H. Miyazawa ◽  
T. Enomoto ◽  
F. Hanaoka ◽  
Y. Kikuchi ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Binding Protein ◽  
Dependent Manner ◽  
Human Homologue ◽  
Gtp Binding Protein ◽  
Gtp Binding

scholarly journals The GTP-binding protein Ypt1 is required for transport in vitro: the Golgi apparatus is defective in ypt1 mutants.

1989 ◽  
Vol 109 (3) ◽  
pp. 1015-1022 ◽  
Author(s):  
R A Bacon ◽  
A Salminen ◽  
H Ruohola ◽  
P Novick ◽  
S Ferro-Novick
Keyword(s):  
Golgi Apparatus ◽  
Binding Protein ◽  
Yeast Cells ◽  
Carboxypeptidase Y ◽  
Loss Of Function ◽  
Gtp Binding Protein ◽  
Gtp Binding ◽  
Transport Defect

The YPT1 gene encodes a raslike, GTP-binding protein that is essential for growth of yeast cells. We show here that mutations in the ypt1 gene disrupt transport of carboxypeptidase Y to the vacuole in vivo and transport of pro-alpha-factor to a site of extensive glycosylation in the Golgi apparatus in vitro. Two different ypt1 mutations result in loss of function of the Golgi complex without affecting the activity of the endoplasmic reticulum or soluble components required for in vitro transport. The function of the mutant Golgi apparatus can be restored by preincubation with wild-type cytosol. The transport defect observed in vitro cannot be overcome by addition of Ca++ to the reaction mixture. We have also established genetic interactions between ypt1 and a subset of the other genes required for transport to and through the Golgi apparatus.

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