Abstract
RhoGDI inhibits guanine nucleotide dissociation from post-translationally processed Rho and Rac proteins but its biochemical role in vivo is unknown. We show here that N-terminal effector site mutations in the Rac protein do not compromise its interaction with RhoGDI and that, whilst geranylgeranylation and -AAX proteolysis of the C-terminal CAAX motif of Rac1 and RhoA are required for efficient interaction with RhoGDI, methylesterification of the C-terminal cysteine residue is not required. In vitro, RhoGDI can form stable complexes with Rho and Rac proteins in both the GTP and GDP bound states. Furthermore the Rac-GTP--RhoGDI complex is resistent to the action of recombinant RhoGAP and recombinant BCR. Thus GDI, by complexing with Rac-GTP and preventing GAP stimulated GTP hydrolysis, may allow transit of the activated form of the Rac protein between physically separated activator and effector proteins in the cell.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adenosine Diphosphate Ribose / metabolism
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Animals
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Base Sequence
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Binding Sites
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Cell Line
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DNA, Single-Stranded
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GTP-Binding Proteins / metabolism
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GTP-Binding Proteins / physiology*
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GTPase-Activating Proteins
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Guanine Nucleotide Dissociation Inhibitors*
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Guanosine Diphosphate / metabolism
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Guanosine Triphosphate / metabolism
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Humans
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Hydrolysis
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Molecular Sequence Data
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Mutation
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Oncogene Proteins / metabolism
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Protein Prenylation
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Protein Processing, Post-Translational
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Protein-Tyrosine Kinases*
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Proteins / antagonists & inhibitors*
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Proteins / metabolism
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Proto-Oncogene Proteins c-bcr
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Proto-Oncogene Proteins*
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Recombinant Proteins / metabolism
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rac GTP-Binding Proteins
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rho Guanine Nucleotide Dissociation Inhibitor alpha
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
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rhoA GTP-Binding Protein
Substances
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ARHGDIA protein, human
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DNA, Single-Stranded
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GTPase-Activating Proteins
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Guanine Nucleotide Dissociation Inhibitors
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Oncogene Proteins
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Proteins
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Proto-Oncogene Proteins
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Recombinant Proteins
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rho Guanine Nucleotide Dissociation Inhibitor alpha
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
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Guanosine Diphosphate
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Adenosine Diphosphate Ribose
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Guanosine Triphosphate
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Protein-Tyrosine Kinases
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BCR protein, human
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Proto-Oncogene Proteins c-bcr
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GTP-Binding Proteins
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rac GTP-Binding Proteins
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rhoA GTP-Binding Protein