The Tek/Tie2 receptor signals through a novel Dok-related docking protein, Dok-R.
Tek/Tie2 is an endothelial cell-specific receptor tyrosine kinase that has been shown to play a role in vascular development of the mouse. Targeted mutagenesis of both Tek and its agonistic ligand, Angiopoietin-1, result in embryonic lethality, demonstrating that the signal transduction pathway(s) mediated by this receptor are crucial for normal embryonic development. In an attempt to identify downstream signaling partners of the Tek receptor, we have used the yeast two-hybrid system to identify phosphotyrosine-dependent interactions. Using this approach, we have identified a novel docking molecule called Dok-R, which has sequence and structural homology to p62dok and IRS-3. Mapping of the phosphotyrosine-interaction domain within Dok-R shows that Dok-R interacts with Tek through a PTB domain. Dok-R is coexpressed with Tek in a number of endothelial cell lines. We show that coexpression of Dok-R with activated Tek results in tyrosine phosphorylation of Dok-R and that rasGAP and Nck coimmunoprecipitate with phosphorylated Dok-R. Furthermore, Dok-R is constitutively bound to Crk presumably through the proline rich tail of Dok-R. The cloning of Dok-R represents the first downstream substrate of the activated Tek receptor, and suggests that Tek can signal through a multitude of pathways.
Ontario Cancer Institutes and Department of Medical Biophysics, University of Toronto, Canada.
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Jones
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Dumont
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020690:GTPase-Activating Proteins; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D008168:Lung / Q000737:chemistry; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry; D015513:Oncogene Proteins / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism; D012313:RNA / Q000032:analysis / Q000235:genetics; D016601:RNA-Binding Proteins; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D042787:Receptor, TIE-2; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000502:physiology; D013154:Spleen / Q000737:chemistry; D014018:Tissue Distribution
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C489560:DOK1 protein, human; C115089:DOK2 protein, human; C489561:Dok1 protein, mouse; C498444:Dok2 protein, mouse; C074561:GAP-associated protein p62; D020690:GTPase-Activating Proteins; C078332:Nck protein; D015513:Oncogene Proteins; D010750:Phosphoproteins; D011506:Proteins; D016601:RNA-Binding Proteins; D019000:Phosphotyrosine; D012313:RNA; D020794:Receptor Protein-Tyrosine Kinases; D042787:Receptor, TIE-2