Differential Signaling by the Focal Adhesion Kinase and Cell Adhesion Kinase β

doi:10.1074/jbc.272.40.25319

Differential Signaling by the Focal Adhesion Kinase and Cell Adhesion Kinase β*

From the Department of Cell Biology and Anatomy and the Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599 and the ^§Department of Biochemistry, Cancer Research Institute, Sapporo Medical Institute, Sapporo 060, Japan

Abstract

pp125^FAK and CAKβ/Pyk2/CadTK/RAFTK are related protein-tyrosine kinases. It is therefore of interest whether CAKβ shares some of the properties of pp125^FAK. Using recombinant glutathioneS-transferase fusion proteins, we show that the C-terminal domains of both proteins bind paxillin in vitro. The C-terminal domain of CAKβ was engineered to be autonomously expressed in chicken embryo cells and, like pp125^FAK and p41/43^FRNK (the C-terminal noncatalytic domain of pp125^FAK), was found to localize to cellular focal adhesions. In contrast, full-length CAKβ was generally found diffusely distributed throughout the cell, although a fraction of the cells exhibited focal adhesion localization. Vanadate treatment of pp125^FAK- and CAKβ-overexpressing CE cells induced a dramatic increase in the phosphotyrosine content of a common set of proteins including tensin, paxillin, and p130^Cas, but some of these substrates, particularly p130^Cas, appeared to be differentially phosphorylated by pp125^FAK and CAKβ. Levels of tyrosine phosphorylation were higher in CAKβ-overexpressing cells, and additional phosphotyrosine-containing species were specifically immunoprecipitated. In addition, vanadate treatment of CE cells overexpressing CAKβ, but not pp125^FAKoverexpressors, induced a profound morphological change, which could be a consequence of the observed differences in substrate phosphorylation.

Footnotes

↵* This project was supported by American Cancer Society Grant CB-173 (to M. D. S.).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.
↵‡ To whom correspondence should be addressed: Dept. of Cell Biology and Anatomy, 534 Tayor Hall, CB# 7090, University of North Carolina, Chapel Hill, NC 27599. Tel.: 919-966-0391; Fax: 919-966-1856; E-mail:Schaller{at}med.unc.edu.
↵1 The abbreviations used are: FAK, focal adhesion kinase; CAKβ, cell adhesion kinase β; FAT, focal adhesion targeting; PTK, protein-tyrosine kinase; CE, chicken embryo; RIPA, radioimmunoprecipitation assay; PAGE, polyacrylamide gel electrophoresis; Cas, Crk-associated substrate; GST, glutathioneS-transferase; FRNK, FAK-related nonkinase; CRNK, CAKβ-related nonkinase; mAb, monoclonal antibody.
↵2 A. Brinson, X. Li, S. Earp, and L. M. Graves, personal communication.
- Received June 27, 1997.
- Revision received July 28, 1997.