The Related Adhesion Focal Tyrosine Kinase Forms a Complex with Paxillin in Hematopoietic Cells

doi:10.1074/jbc.271.49.31222

The Related Adhesion Focal Tyrosine Kinase Forms a Complex with Paxillin in Hematopoietic Cells*

From the ^‡ Division of Hematologic Malignancies, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115 and
^§ Division of Hematology and Oncology, Deaconess Hospital and Harvard Medical School, Boston, Massachusetts 02115

^¶ To whom correspondence should be addressed:
Division of Hematologic Malignancies, Dana-Farber Cancer Institute and Harvard Medical School, 44 Binney St., Boston, MA, 02115.
Tel.: 617-632-3360; Fax: 617-632-4388.

Abstract

Related adhesion focal tyrosine kinase (RAFTK), also known as proline-rich tyrosine kinase 2 and cellular adhesion kinase β, has been recently cloned and characterized as a member of the focal adhesion kinase (FAK) subfamily. RAFTK has an overall 48% amino acid homology to p125^FAK and contains a kinase domain but lacks a transmembrane region, myristylation sites, and Src homology region 2 and 3 domains. By Northern blot analysis, RAFTK is expressed in myeloid, lymphoid, and megakaryocytic hematopoietic cells. Like p125^FAK, we found that RAFTK interacts with the focal adhesion protein paxillin. In the lymphoid cell line BaF3 and the myeloid cell line 32Dcl3, RAFTK coprecipitates with paxillin. Using in vitro binding assays, RAFTK and paxillin were shown to bind directly, through a segment of paxillin that required amino acids 100-227 and a domain in the C terminus of RAFTK. In vitro, RAFTK could phosphorylate paxillin on tyrosine residues. These results suggest that RAFTK, as well as p125^FAK, may be important in phosphotyrosine-signaling events within the focal adhesion.

Footnotes

↵* This work was supported by National Institutes of Health Grants CA60821 (to R. S.), HL55445 (to S. A.), HL51456 (to H. A.), and CA36167 (to J. D. 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:

RAFTK

related adhesion focal tyrosine kinase

FAK

focal adhesion kinase

GST

glutathione S-transferase

IL

interleukin

PYK

proline-rich tyrosine kinase

SH2

Src homology region 2

SH3

Src homology region 3

PAGE

polyacrylamide gel electrophoresis.
- Received May 21, 1996.
- Revision received September 23, 1996.