The adapter protein APS associates with the multifunctional docking sites Tyr-568 and Tyr-936 in c-Kit.
The adapter protein APS has previously been shown to be involved in recruiting the ubiquitin E3 ligase c-Cbl to the insulin receptor, the platelet-derived growth factor beta-receptor and the erythropoietin receptor, leading to increased degradation of the receptors and inhibition of mitogenesis. Here we demonstrate, by use of immobilized synthetic phosphopeptides corresponding to various autophosphorylated tyrosine residues in the receptor for stem-cell factor (c-Kit), that APS preferentially associates with phosphorylated Tyr-568 and Tyr-936. Tyr-568 has previously been identified as the binding site of the Src family of tyrosine kinases, the Csk-homologous kinase CHK, and the protein tyrosine phosphatase SHP-2. We have recently demonstrated that Tyr-936 is an autophosphorylation site involved in binding the adapter proteins Grb2 and Grb7. We could further demonstrate that the critical determinant for binding of APS is the presence of either a leucine or an isoleucine residue in the position +3 to the phosphorylated tyrosine. This allowed us to design mutants that selectively failed to associate with APS, while still associating with Src family members, SHP-2 and Grb2, respectively.
Wollberg
Patrik
P
Ludwig Institute for Cancer Research, Biomedical Centre, P.O. Box 595, SE-751 24 Uppsala, Sweden.
Lennartsson
Johan
J
Gottfridsson
Eva
E
Yoshimura
Akihiko
A
Rönnstrand
Lars
L
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D006801:Humans; D007532:Isoleucine / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000378:metabolism*; D017479:Receptors, Platelet-Derived Growth Factor / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D019089:Stem Cell Factor / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D010455:Peptides; D011506:Proteins; D011993:Recombinant Fusion Proteins; C107249:SH2B2 protein, human; C488161:Sh2b2 protein, mouse; D019089:Stem Cell Factor; D007532:Isoleucine; D014443:Tyrosine; D019009:Proto-Oncogene Proteins c-kit; D017479:Receptors, Platelet-Derived Growth Factor; D007930:Leucine