PMID:10102632

Citation	Dougher, M and Terman, BI (1999) Autophosphorylation of KDR in the kinase domain is required for maximal VEGF-stimulated kinase activity and receptor internalization. Oncogene 18:1619-27
Abstract	We have previously reported the identification of four autophosphorylation sites on the KDR VEGF receptor. Two of these sites (tyrosines 951 and 996) are located in the receptor's kinase insert domain, and two (tyrosines 1054 and 1059) are located in the catalytic domain. In order to clarify the functional significance of these sites, we made DNA constructs in which tyrosine codons were replaced with those for phenylalanine, and expressed the DNA constructs in 293 cells. VEGF binding to cells expressing the native receptor led to a rapid increase in receptor and PLC-gamma phosphorylation, and a slower increase in the phosphorylation of p125FAK and paxillin. VEGF binding to KDR(Y951F) and KDR(Y996F) expressing cells resulted in phosphorylation of all cellular substrates tested, although the level of PLCgamma phosphorylation was decreased for KDR(Y996F). The decreased level of PLCgamma phosphorylation was not because PLCgamma-containing SH2 domains bind to the Y996 autophosphorylation site. We conclude that there exists receptor autophosphorylation sites not previously identified which allow for signaling via PLCgamma, as well as p125FAK and paxillin. VEGF binding to cells expressing KDR mutated at both tyrosine's 1054 and 1059 activated receptor autophosphorylation but at a level which was only 10% of that seen for cells expressing native receptor. Tyrosine phosphorylation of cell signaling proteins was not observed in KDR(Y1054,1059) expressing cells. Utilizing an in vitro assay which directly measures receptor catalytic activity allowed us to determine that the tyrosine kinase activity of the native receptor was significantly greater than that for the double mutant. We conclude from this result that VEGF-induced autophosphorylation at tyrosines 1054 and 1059 is a required step for allowing maximal KDR kinase activity. Maximal rates of receptor kinase activity is required for VEGF-induced receptor internalization, as internalization was delayed in the KDR(Y1054,1059F) expressing cells when compared to cells expressing native receptor.
Links	PubMed Online version:10.1038/sj.onc.1202478
Keywords	Amino Acid Substitution; Catalysis; Catalytic Domain; Cell Adhesion Molecules/metabolism; Cell Line, Transformed; Codon/genetics; Cytoskeletal Proteins/metabolism; Endocytosis/physiology; Endothelial Growth Factors/pharmacology; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; Humans; Isoenzymes/metabolism; Kidney; Lymphokines/pharmacology; Mutagenesis, Site-Directed; Neovascularization, Physiologic/physiology; Paxillin; Phospholipase C gamma; Phosphoproteins/metabolism; Phosphorylation; Phosphotyrosine/physiology; Protein Processing, Post-Translational; Protein-Tyrosine Kinases/metabolism; Receptor Protein-Tyrosine Kinases/chemistry; Receptor Protein-Tyrosine Kinases/metabolism; Receptors, Growth Factor/chemistry; Receptors, Growth Factor/metabolism; Receptors, Vascular Endothelial Growth Factor; Structure-Activity Relationship; Type C Phospholipases/metabolism; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors; src Homology Domains
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:VGFR2	located_in	GO:0005887: integral component of plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
HUMAN:VGFR2	involved_in	GO:0048010: vascular endothelial growth factor receptor signaling pathway	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:VGFR2	involved_in	GO:0046777: protein autophosphorylation	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:VGFR2	involved_in	GO:0035924: cellular response to vascular endothelial growth factor stimulus	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:VGFR2	involved_in	GO:0018108: peptidyl-tyrosine phosphorylation	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:VGFR2	part_of	GO:0005887: integral component of plasma membrane	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
HUMAN:VGFR2	enables	GO:0005021: vascular endothelial growth factor-activated receptor activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

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