How does arrestin assemble MAPKs into a signaling complex?
Arrestins bind active phosphorylated G protein-coupled receptors, precluding G protein activation and channeling signaling to alternative pathways. Arrestins also function as mitogen-activated protein kinase (MAPK) scaffolds, bringing together three components of MAPK signaling modules. Here we have demonstrated that all four vertebrate arrestins interact with JNK3, MKK4, and ASK1, but only arrestin3 facilitates JNK3 activation. Thus, the functional specificity of arrestins is not determined by differential binding of the kinases. Using receptor binding-impaired mutant, we have shown that free arrestin3 readily promotes JNK3 phosphorylation. We identified key arrestin-binding elements in JNK3 and ASK1 and investigated the molecular interactions of arrestin2 and arrestin3 and their individual domains with the components of the two MAPK cascades, ASK1-MKK4-JNK3 and c-Raf-1-MEK1-ERK2. We found that both arrestin domains interact with all six kinases. These findings shed new light on the mechanism of arrestin-mediated MAPK activation and the spatial arrangement of the three kinases on arrestin molecule.
Song
Xiufeng
X
Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232 and the Department of Pharmacology, Emory University, Atlanta, Georgia 30322.
Coffa
Sergio
S
Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232 and the Department of Pharmacology, Emory University, Atlanta, Georgia 30322.
Fu
Haian
H
Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232 and the Department of Pharmacology, Emory University, Atlanta, Georgia 30322.
Gurevich
Vsevolod V
VV
Department of Pharmacology, Vanderbilt University, Nashville, Tennessee 37232 and the Department of Pharmacology, Emory University, Atlanta, Georgia 30322. Electronic address: vsevolod.gurevich@vanderbilt.edu.
D000818:Animals; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002417:Cattle; D002522:Chlorocebus aethiops; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology
D019390:Arrestins; D009097:Multienzyme Complexes; C082333:arrestin3; D020929:Mitogen-Activated Protein Kinase Kinases