RhoGDI-binding-defective mutant of Cdc42Hs targets to membranes and activates filopodia formation but does not cycle with the cytosol of mammalian cells
| Autor: | R M, Gibson, A L, Wilson-Delfosse |
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| Rok vydání: | 2001 |
| Předmět: |
Models
Molecular rho Guanine Nucleotide Dissociation Inhibitor alpha Protein Conformation Protein Prenylation In Vitro Techniques Models Biological Recombinant Proteins Cell Line Rats Cytosol Microsomes Mutagenesis Site-Directed Animals Humans Point Mutation rho-Specific Guanine Nucleotide Dissociation Inhibitors Pseudopodia cdc42 GTP-Binding Protein Guanine Nucleotide Dissociation Inhibitors Protein Binding Subcellular Fractions Research Article |
| Zdroj: | The Biochemical journal. 359(Pt 2) |
| ISSN: | 0264-6021 |
| Popis: | We have identified a mutant of the human G-protein Cdc42Hs, R66E, that fails to form a detectable complex with the GDP-dissociation inhibitor RhoGDI in cell-free systems or in intact cells. This point mutant is prenylated, binds guanine nucleotide and interacts with GTPase-activating protein in a manner indistinguishable from wild-type Cdc42Hs. Immunofluorescence localization studies revealed that this RhoGDI-binding-defective mutant is found predominantly in the Golgi apparatus, with a staining pattern similar to that of the wild-type protein. However, unlike wild-type Cdc42Hs, which is distributed in both the microsomal membrane and cytosolic fractions, studies using differential centrifugation show that prenylated R66E Cdc42Hs is found exclusively in association with lipid bilayers. Additionally, whereas the overexpression of RhoGDI results in an apparent translocation of wild-type Cdc42Hs from the Golgi apparatus into the cytosol, identical RhoGDI-overexpression conditions do not alter the Golgi localization of the R66E mutant. Furthermore, overexpression of this RhoGDI-binding-defective mutant of Cdc42Hs seems to activate redistribution of the actin cytoskeleton and filopodia formation in fibroblasts in a manner indistinguishable from the wild-type protein. Taken together, these results suggest that the interaction of Cdc42Hs with RhoGDI is not essential for proper membrane targeting of nascent prenylated Cdc42Hs in mammalian cells; neither is this interaction an essential part of the mechanism by which Cdc42Hs activates filopodia formation. However, it does seem that redistribution of Cdc42Hs to the cytosolic compartment is absolutely dependent on RhoGDI interaction. |
| Databáze: | OpenAIRE |
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