Quantifying ERK2-protein interactions by fluorescence anisotropy: PEA-15 inhibits ERK2 by blocking the binding of DEJL domains.
While mitogen-activated protein kinase signaling pathways constitute highly regulated networks of protein-protein interactions, little quantitative information for these interactions is available. Here we highlight recent fluorescence anisotropy binding studies that focus on the interactions of ERK1 and ERK2 with PEA-15 (antiapoptotic phosphoprotein enriched in astrocytes-15 kDa), a small protein that sequesters ERK2 in the cytoplasm. The regulation of ERK2 by PEA-15 is appraised in the light of a simple equilibrium-binding model for reversible ERK2 nucleoplasmic-cytoplasmic shuttling, which elaborates on the theory of Burack and Shaw (J. Biol. Chem. 280, 3832-3837; 2005). Also highlighted is the recent observation that the peptide N-QKGKPRDLELPLSPSL-C, derived from the docking site for ERK/JNK and LEL (DEJL) in Elk-1, displaces PEA-15 from ERK2. It is proposed that the C-terminus of PEA-15 ((121)LXLXXXXKK(129)) is a reverse DEJL domain [which has a general consensus of R/K-phi(A)-X(3/4)-phi(B), where phi(A) and phi(B) are hydrophobic residues (Leu, Ile, or Val)], which mediates one arm of a bidentate PEA-15 interaction with ERK2. The notion that PEA-15 is a potent inhibitor of many ERK2-mediated phosphorylations, by virtue of its ability to block ERK2-DEJL domain interactions, is proposed.
Callaway
Kari
K
Graduate Program in Biochemistry, University of Texas at Austin, TX 78712, USA.
Rainey
Mark A
MA
Dalby
Kevin N
KN
D021581:Active Transport, Cell Nucleus; D000818:Animals; D051017:Apoptosis Regulatory Proteins; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D005454:Fluorescence Polarization / Q000379:methods*; D006801:Humans; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D010750:Phosphoproteins / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding / Q000187:drug effects* / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000187:drug effects
D051017:Apoptosis Regulatory Proteins; C490443:Pea15 protein, rat; D010750:Phosphoproteins; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3