Interaction of G protein Gβγ dimers with small GTP-binding proteins of the Rho family

FEBS Letters ◽  
1996 ◽  
Vol 399 (3) ◽  
pp. 211-214 ◽  
Author(s):  
Rainer Harhammer ◽  
Antje Gohla ◽  
Günter Schultz
Keyword(s):  
G Protein ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

Relationship of GTP-binding proteins, phospholipase C, and PGE2 synthesis in rat glomerular mesangial cells

1989 ◽  
Vol 256 (1) ◽  
pp. F171-F178 ◽  
Author(s):  
D. Schlondorff ◽  
P. Singhal ◽  
A. Hassid ◽  
J. A. Satriano ◽  
S. DeCandido
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase C ◽  
G Protein ◽  
Binding Proteins ◽  
Mesangial Cells ◽  
Cdna Probe ◽  
Ang Ii ◽  
Glomerular Mesangial Cells ◽  
Gtp Binding Proteins ◽  
Gtp Binding

We evaluated the role of GTP-binding proteins in the activation of phospholipase C, release of arachidonic acid, and synthesis of prostaglandin (PG) E2 in response to platelet-activating factor (PAF) and angiotensin II (ANG II) in cultured rat mesangial cells. Pretreatment with pertussis toxin (PT) decreased PGE2 formation and arachidonic acid release in response to PAF and ANG II but not that to A 23187. PT pretreatment also inhibited formation of inositol trisphosphate (IP3) in response to ANG II or PAF but did not significantly alter the rise in intracellular calcium detected by fura-2. PT catalyzed ADP ribosylation of two proteins of molecular mass approximately 40 and 41 kDa. Further evidence for involvement of GTP-binding protein in phospholipase C activation was that GTP-gamma S stimulated IP3 generation. Immunoblots with antibodies directed against different inhibitory alpha subunits of GTP-binding proteins showed that the major 40-kDa PT substrate reacted with an antibody directed against a decapeptide of the G protein subunit alpha i2 that is also found in leukocytes. This was further confirmed by Northern blot that showed the existence of mRNA in mesangial cells that hybridized with a cDNA probe for G alpha i2. In addition lesser amounts of mRNA hybridized with a restriction fragment cDNA probe for G alpha i3, which corresponds to the 41-kDa substrate for PT ribosylation. These results show that phospholipase C activation by PAF and ANG II in mesangial cells involves a specific G protein, most likely G alpha i2.(ABSTRACT TRUNCATED AT 250 WORDS)

Rho family small GTP-binding proteins in growth cone signalling

1997 ◽  
Vol 7 (1) ◽  
pp. 81-86 ◽  
Author(s):  
Liqun Luo ◽  
Lily Y Jan ◽  
Yuh-Nung Jan
Keyword(s):  
Growth Cone ◽  
Binding Proteins ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

scholarly journals Rac GTPase interacts specifically with phosphatidylinositol 3-kinase

1996 ◽  
Vol 315 (3) ◽  
pp. 775-779 ◽  
Author(s):  
Gary M. BOKOCH ◽  
Chris J. VLAHOS ◽  
Yan WANG ◽  
Ulla G. KNAUS ◽  
Alexis E. TRAYNOR-KAPLAN
Keyword(s):  
Growth Factor ◽  
Actin Polymerization ◽  
Binding Proteins ◽  
Specific Interaction ◽  
Bound State ◽  
Rac Gtpase ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Rho Family

The Rac GTP-binding proteins are members of the Rho family and regulate growth factor-stimulated actin assembly in a variety of cells. The formation of phosphorylated inositol lipids has been implicated in control of the processes initiating and regulating such actin polymerization. Associations of Rho family GTP-binding proteins with enzymes involved in lipid metabolism have been described. Here we demonstrate a direct and specific interaction of Rac proteins with phosphatidylinositol (PI) 3-kinase. This interaction is dependent upon Rac being in a GTP-bound state and requires an intact Rac effector domain. In contrast, direct binding of RhoA to PI 3-kinase could not be detected. Rac–GTP also bound to PI 3-kinase in Swiss 3T3 fibroblast and human neutrophil lysates, and increased PI 3-kinase activity became associated with Rac–GTP in platelet-derived growth factor-stimulated cells. Interaction of Rac–GTP with PI 3-kinase in vitro stimulated the activity of the enzyme by 2–9-fold. A specific interaction of active Rac with PI 3-kinase might be important in regulation of the actin cytoskeleton.

scholarly journals A novel member of the rho family of small GTP-binding proteins is specifically required for cytokinesis.

1996 ◽  
Vol 133 (6) ◽  
pp. 1321-1329 ◽  
Author(s):  
D A Larochelle ◽  
K K Vithalani ◽  
A De Lozanne
Keyword(s):  
Binding Proteins ◽  
Molecular Genetic ◽  
Genetic Screen ◽  
Phenotypic Characterization ◽  
Essential Requirement ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Subcellular Processes ◽  
Rho Family

Several members of the rho/rac family of small GTP-binding proteins are known to regulate the distribution of the actin cytoskeleton in various subcellular processes. We describe here a novel rac protein, racE, which is specifically required for cytokinesis, an actomyosin-mediated process. The racE gene was isolated in a molecular genetic screen devised to isolate genes required for cytokinesis in Dictyostelium. Phenotypic characterization of racE mutants revealed that racE is not essential for any other cell motility event, including phagocytosis, chemotaxis, capping, or development. Our data provide the first genetic evidence for the essential requirement of a rho-like protein, specifically in cytokinesis, and suggest a role for these proteins in coordinating cytokinesis with the mitotic events of the cell cycle.

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