IQGAP1, a calmodulin-binding protein with a rasGAP-related domain, is a potential effector for cdc42Hs
| Autor: | Hart, M J, Callow, M G, Souza, B, Polakis, P |
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| Jazyk: | angličtina |
| Rok vydání: | 1996 |
| Předmět: |
DNA
Complementary Base Sequence Sequence Homology Amino Acid Cell Membrane Molecular Sequence Data Cell Cycle Proteins Immunohistochemistry Chromatography Affinity Cell Line GTP Phosphohydrolases Calmodulin GTP-Binding Proteins ras GTPase-Activating Proteins Animals Calmodulin-Binding Proteins Amino Acid Sequence Cloning Molecular Carrier Proteins cdc42 GTP-Binding Protein Research Article Protein Binding |
| Popis: | Proteins that associate with the GTP-bound forms of the Ras superfamily of proteins are potential effector targets for these molecular switches. A 195 kDa protein was purified from cell lysates by affinity chromatography on immobilized cdc42Hs-GTP and a corresponding cDNA was isolated. Sequence analysis revealed localized identities to calponin, the WW domain, unconventional myosins and to the rasGAP-related domain (GRD) contained in IRA, NF-1, SAR1 and rasGAP. p195 was found to be identical to IQGAP1, a protein previously reported to bind ras. Purified recombinant p195/IQGAP1 bound to and inhibited the GTPase activity of cdc42Hs and rac whereas no interaction with ras was detected. The C-terminal half of IQGAP1 containing the GRD bound to cdc42 and rac in a GRD-dependent fashion, but a smaller fragment containing only the GRD did not. Cdc42 was also co-immunoprecipitated from cell lysates with antibody specific to p195/IQGAP1. Calmodulin also co-immunoprecipitated with p195/IQGAP1 and was found to associate with fragments containing the IQ domain. Expression of a cDNA fragment encoding the GRD inhibited the CDC24/CDC42 pathway in yeast, but no effect on ras was observed. In mammalian cells, both endogenous and ectopically expressed p195/IQGAP1 were localized to lamellipodia and ruffling cell membranes, where co-localization with actin was apparent. These results suggest that IQGAP1 is an effector target for cdc42Hs and may mediate the effects of this GTPase on cell morphology. |
| Databáze: | OpenAIRE |
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