Stress-activated Protein Kinase-3 Interacts with the PDZ Domain of α1-Syntrophin

doi:10.1074/jbc.274.18.12626

Stress-activated Protein Kinase-3 Interacts with the PDZ Domain of α1-Syntrophin

A MECHANISM FOR SPECIFIC SUBSTRATE RECOGNITION*

From the ^‡Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom, the ^¶Medical Research Council Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, MSI/WTB Complex, Dundee DD1 5EH, United Kingdom, and the ^‖Department of Neurology, E.D. Adrian Building, University of Cambridge, Robinson Way, Cambridge CB2 2PY, United Kingdom

Abstract

Mechanisms for selective targeting to unique subcellular sites play an important role in determining the substrate specificities of protein kinases. Here we show that stress-activated protein kinase-3 (SAPK3, also called ERK6 and p38γ), a member of the mitogen-activated protein kinase family that is abundantly expressed in skeletal muscle, binds through its carboxyl-terminal sequence -KETXL to the PDZ domain of α1-syntrophin. SAPK3 phosphorylates α1-syntrophin at serine residues 193 and 201 in vitro and phosphorylation is dependent on binding to the PDZ domain of α1-syntrophin. In skeletal muscle SAPK3 and α1-syntrophin co-localize at the neuromuscular junction, and both proteins can be co-immunoprecipitated from transfected COS cell lysates. Phosphorylation of a PDZ domain-containing protein by an associated protein kinase is a novel mechanism for determining both the localization and the substrate specificity of a protein kinase.

Footnotes

↵* This work was supported by the United Kingdom Medical Research Council (to P. C. and M. G.) and by the Royal Society (to M. G. S. and P. C.).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.
↵§ Recipient of a post-doctoral fellowship from the Human Frontier Science Program and supported by Innogenetics Inc.
↵** Awarded a Wellcome Trust Prize studentship.
↵‡ Supported by a post-doctoral fellowship from Novartis A.G.
↵§§ To whom correspondence should be addressed. Tel.: 1223-402036; Fax: 1223-213556.
↵2 M. Hasegawa, A. Cuenda, M. G. Spillantini, G. M. Thomas, V. Buée-Scherrer, P. Cohen, and M. Goedert, unpublished observations.
Abbreviations:

SAPK

stress-activated protein kinase

MAPK

mitogen-activated protein kinase

GST

glutathione S-transferase

ELISA

enzyme-linked immunosorbent assay

PBS

phosphate-buffered saline

MBP

myelin basic protein
- Received November 24, 1998.
The American Society for Biochemistry and Molecular Biology, Inc.