IQGAP1, a Rac- and Cdc42-binding Protein, Directly Binds and Cross-links Microfilaments
| Autor: | Aaron T. Fullerton, George S. Bloom, Anne Marie Bashour, Matthew J. Hart |
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| Rok vydání: | 1997 |
| Předmět: |
Molecular Sequence Data
macromolecular substances Biology Microfilament Article 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine IQGAP1 Calmodulin Adrenal Glands Animals Cytochalasin Amino Acid Sequence Actin 030304 developmental biology 0303 health sciences Binding Sites Cell Biology Actin cytoskeleton 3. Good health Cell biology Actin Cytoskeleton chemistry Cdc42 GTP-Binding Protein ras GTPase-Activating Proteins Cattle Lamellipodium Carrier Proteins Filopodia 030217 neurology & neurosurgery Protein Binding |
| Zdroj: | The Journal of Cell Biology |
| ISSN: | 1540-8140 0021-9525 |
| DOI: | 10.1083/jcb.137.7.1555 |
| Popis: | Activated forms of the GTPases, Rac and Cdc42, are known to stimulate formation of microfilament-rich lamellipodia and filopodia, respectively, but the underlying mechanisms have remained obscure. We now report the purification and characterization of a protein, IQGAP1, which is likely to mediate effects of these GTPases on microfilaments. Native IQGAP1 purified from bovine adrenal comprises two ∼190-kD subunits per molecule plus substoichiometric calmodulin. Purified IQGAP1 bound directly to F-actin and cross-linked the actin filaments into irregular, interconnected bundles that exhibited gel-like properties. Exogenous calmodulin partially inhibited binding of IQGAP1 to F-actin, and was more effective in the absence, than in the presence of calcium. Immunofluorescence microscopy demonstrated cytochalasin D–sensitive colocalization of IQGAP1 with cortical microfilaments. These results, in conjunction with prior evidence that IQGAP1 binds directly to activated Rac and Cdc42, suggest that IQGAP1 serves as a direct molecular link between these GTPases and the actin cytoskeleton, and that the actin-binding activity of IQGAP1 is regulated by calmodulin. |
| Databáze: | OpenAIRE |
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