Accumulating evidence indicates that the β-arrestins act as scaffold molecules that couple G-protein-coupled receptors to mitogen-activated protein (MAP) kinase signaling pathways. Recently, we identified the c-Jun N-terminal kinase 3 (JNK3) as a β-arrestin2-interacting protein in yeast-two hybrid and co-immunoprecipitation studies. β-Arrestin2 acts as a scaffold to enhance signaling to JNK3 stimulated by overexpression of the MAP3 kinase ASK1 or by agonist activation of the angiotensin 1A receptor. Whereas β-arrestin2 is a very strong activator of JNK3 signaling, β-arrestin1 is very weak in this regard. The data also indicate that the specific step enhanced by β-arrestin2 involves phosphorylation of JNK3 by the MAP2 kinase MKK4. We reasoned that defining the region (or domain) in β-arrestin2 responsible for high level JNK3 activation would provide insight into the mechanism by which β-arrestin2 enhances the activity of this signaling pathway. Using chimeric β-arrestins, we have determined that sequences in the carboxyl-terminal region of β-arrestin2 are important for the enhancement of JNK3 phosphorylation. More detailed analysis of the carboxyl-terminal domains of the β-arrestins indicated that β-arrestin2, but not β-arrestin1, contains a sequence (RRSLHL) highly homologous to the conserved docking motif present in many MAP kinase-binding proteins. Replacement of the β-arrestin2 RRS residues with the corresponding KP residues present in β-arrestin1 dramatically reduced both JNK3 interaction and enhancement of JNK3 phosphorylation. Conversely, replacement of the KP residues in β-arrestin1 with RRS significantly increased both JNK3 binding and enhancement of JNK3 phosphorylation. These results delineate a mechanism by which β-arrestin2 functions as a scaffold protein in the JNK3 signaling pathway and implicate the conserved docking site in β-arrestin2 as an important factor in binding JNK3 and stimulating the phosphorylation of JNK3 by MKK4.
CITATION STYLE
Miller, W. E., McDonald, P. H., Cai, S. F., Field, M. E., Davis, R. J., & Lefkowitz, R. J. (2001). Identification of a Motif in the Carboxyl Terminus of β-Arrestin2 Responsible for Activation of JNK3. Journal of Biological Chemistry, 276(30), 27770–27777. https://doi.org/10.1074/jbc.M102264200
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