Phosphorylation of Tyrosine 397 in Focal Adhesion Kinase Is Required for Binding Phosphatidylinositol 3-Kinase

doi:10.1074/jbc.271.42.26329

Phosphorylation of Tyrosine 397 in Focal Adhesion Kinase Is Required for Binding Phosphatidylinositol 3-Kinase*

From the Cancer Biology Laboratories, Department of Pathology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853

^§ To whom correspondence should be addressed. Fax: 607-253-3317.

↵^‡ Present address: Center for Extracellular Matrix Biology, Texas A & M University, Houston, TX 77030.

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.

Footnotes

↵* This research was supported by National Institutes of Health Grants GM48050 and GM52890 (to J.-L. G.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

FAK

focal adhesion kinase

PI

phosphatidylinositol

GST

glutathione S-transferase

PDGF

platelet-derived growth factor

HA

hemagglutinin

kd

kinase-defective.
- Received May 2, 1996.
- Revision received August 12, 1996.