Differential interaction of CrkII adaptor protein with platelet-derived growth factor alpha- and beta-receptors is determined by its internal tyrosine phosphorylation.
CrkII is an intracellular adaptor protein involved in signal transduction by various growth factors. Activation of PDGF alpha-receptor resulted in its association with CrkII in vivo. In contrast, binding of CrkII to the PDGF beta-receptor was negligible, despite its becoming prominently phosphorylated. Bacterially expressed GST-CrkII SH2 domain specifically bound to Tyr-762 and Tyr-771 in the activated PDGF alpha- and beta- receptors, respectively. GST fusion protein of full-length CrkII also bound to the activated PDGF beta-receptor. However, tyrosine phosphorylation of GST-CrkII diminished its binding to the beta-receptor. CrkI, a truncated version of CrkII lacking the phosphorylatable tyrosine residue, could bind to both PDGF alpha- and beta-receptors in vivo. In conclusion, tyrosine phosphorylation of CrkII negatively affects its binding to the PDGF receptors. The differential binding of CrkII to the PDGF alpha- and beta- receptors may be a rationale for functional diversity between the two receptors.
Pubmed ID: 10733900 RIS Download
Animals | Models, Biological | Phosphorylation | Platelet-Derived Growth Factor | Protein Binding | Protein Kinases | Proto-Oncogene Proteins | Proto-Oncogene Proteins c-crk | Receptor, Platelet-Derived Growth Factor alpha | Receptor, Platelet-Derived Growth Factor beta | Recombinant Fusion Proteins | Signal Transduction | Swine | Tyrosine | src Homology Domains