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Identification of phosphorylated proteins associated with the fibroblast growth factor receptor type I during early
P J Ryan1, G D Paterno, L L Gillespie
1Terry Fox Cancer Research Laboratories, Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Canada.
Abstract:
Signaling through the FGF receptor (FGFR) is required for mesoderm induction in Xenopus. Some of the downstream signaling molecules implicated in this developmental process include Ras, Raf and MAP kinase. In a previous report, we demonstrated that PLC gamma 1, Grb-2, SOS and Nck were associated with activated FGFR1s in a signaling complex in Xenopus blastulae. In addition, several unidentified phosphotyrosylproteins were present in the FGFR1 complex. Here we identify three of these proteins as Ras-GAP, the p85 of P13'K and SHP2, while demonstrating that c-Src and She were not associated with the FGFR1. Furthermore, we show that three additional phosphotyrosylproteins from the FGFR1 complex specifically bound to the adaptor molecule Nck.
Insights
Fibroblast growth factor receptor (FGFR) signaling in Xenopus involves Ras, Raf, and MAP kinase. This study identifies Ras-GAP, p85 of PI3K, and SHP2 as key components of the FGFR1 signaling complex.
Area of Science:
- Developmental Biology
- Molecular Signaling
- Cell Biology
Background:
- Fibroblast growth factor receptor (FGFR) signaling is crucial for mesoderm induction in Xenopus development.
- Downstream signaling molecules like Ras, Raf, and MAP kinase are implicated in this process.
- Previous work identified PLC gamma 1, Grb-2, SOS, and Nck in activated FGFR1 signaling complexes.
Purpose of the Study:
- To identify unknown phosphotyrosylproteins associated with activated FGFR1 in Xenopus blastulae.
- To determine the association of c-Src and She with FGFR1.
- To investigate the binding of FGFR1 complex phosphotyrosylproteins to the adaptor molecule Nck.
Main Methods:
- Biochemical analysis of activated FGFR1 complexes from Xenopus blastulae.
- Identification of associated phosphotyrosylproteins using immunoprecipitation and mass spectrometry.
- Assessment of protein-protein interactions using binding assays.
Main Results:
- Ras-GAP, the p85 subunit of PI3K, and SHP2 were identified within the FGFR1 signaling complex.
- c-Src and She were found not to be associated with activated FGFR1.
- Three novel phosphotyrosylproteins from the FGFR1 complex were shown to specifically bind to the adaptor protein Nck.
Conclusions:
- The study expands the known components of the FGFR1 signaling complex involved in mesoderm induction.
- Identification of Ras-GAP, p85 PI3K, and SHP2 provides further insight into downstream signaling pathways.
- Specific binding of phosphotyrosylproteins to Nck highlights the role of adaptor proteins in signal transduction.