Enhancement of Guanine-Nucleotide Exchange Activity of C3G for Rap1 by the Expression of Crk, CrkL, and Grb2
| Autor: | Tamotsu Ichiba, Michiyuki Matsuda, Osamu Sakai, John Groffen, Takeshi Kurata, Seisuke Hattori, Satoshi Nagata, Yasunobu Kuraishi |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
animal structures
Guanine Eukaryotic Initiation Factor-2 Protozoan Proteins SH2 domain Biochemistry Catalysis src Homology Domains Adapter molecule crk chemistry.chemical_compound GTP-Binding Proteins Proto-Oncogene Proteins Animals Guanine Nucleotide Exchange Factors Molecular Biology Adaptor Proteins Signal Transducing GRB2 Adaptor Protein Epidermal Growth Factor biology Chemistry Nuclear Proteins Proteins Signal transducing adaptor protein Cell Biology Proto-Oncogene Proteins c-crk Cell biology ErbB Receptors CRKL rap GTP-Binding Proteins COS Cells embryonic structures biology.protein ras Guanine Nucleotide Exchange Factors Rap1 GRB2 Guanine nucleotide exchange factor Protein Kinases Transcription Factors |
| Zdroj: | Journal of Biological Chemistry. 272:22215-22220 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.272.35.22215 |
| Popis: | Crk is an adaptor protein that consists almost entirely of SH2 and SH3 domains. We have previously demonstrated, by using in vivo and in vitro systems, that C3G, which was identified as a Crk SH3 domain-binding guanine nucleotide exchange factor, specifically activates Rap1. C3G also binds to other adaptor proteins, including CrkL and Grb2. In the present study, we analyzed the effect of Crk, CrkL, and Grb2 on the C3G-Rap1 pathway. Expression of Crk, CrkL, and Grb2 with C3G in Cos1 cells significantly increased the ratio of GTP/GDP bound to Rap1. Both the SH2 and SH3 domains of Crk were required for this activity. However, Crk did not stimulate the guanine nucleotide exchange activity of C3G for Rap1in vitro, suggesting that Crk does not activate C3G by an allosteric mechanism. The requirement of the SH2 domain of Crk for the enhancement of guanine nucleotide exchange activity for Rap1 could be compensated for by the addition of a farnesylation signal to Crk, indicating that Crk enhanced the guanine nucleotide exchange activity of C3G by membrane recruitment of C3G. These results demonstrate that Crk, CrkL, and Grb2 positively modulate the C3G-Rap1 pathway primarily by recruiting C3G to the cell membrane. |
| Databáze: | OpenAIRE |
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