title: Phosphorylation of tyrosine 397 in focal adhesion kinase is required for binding phosphatidylinositol 3-kinase.
abstract: We have shown previously that cell adhesion or platelet-derived growth factor (PDGF) promotes the in vivo association of focal adhesion kinase (FAK) with phosphatidylinositol (PI) 3-kinase. In vitro experiments indicated that this interaction was mediated by the p85 subunit of PI 3-kinase and dependent on the tyrosine phosphorylation of FAK. Here we report data suggesting that the major autophosphorylation site of FAK (Tyr-397) is the binding site for the SH2 domains of p85 in vitro and is also required for the association of FAK with PI 3-kinase in vivo. We also show that Tyr-397 is responsible for the increased FAK:PI 3-kinase association upon PDGF stimulation, implying that no additional site of FAK was involved in its binding to PI 3-kinase after PDGF stimulation. Finally, we present evidence that the interaction of PI 3-kinase with Tyr-397 of FAK stimulates its activity. Together, these results suggest that FAK activation and autophosphorylation at Tyr-397 may lead to its association with PI 3-kinase through the SH2 domains of p85, which can subsequently activate PI 3-kinase during cell adhesion.
authors.affiliation: Cancer Biology Laboratories, Department of Pathology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA.
authors.forename: H C
authors.initials: HC
authors.lastname: Chen
authors.forename: P A
authors.initials: PA
authors.lastname: Appeddu
authors.forename: H
authors.initials: H
authors.lastname: Isoda
authors.forename: J L
authors.initials: JL
authors.lastname: Guan
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D015815:Cell Adhesion Molecules; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse