title: Selectivity of docking sites in MAPK kinases.
abstract: Protein kinases often recognize their substrates and regulators through docking interactions that occur outside of the active site; these interactions can help us to understand kinase networks, and to target kinases with drugs. During mitogen-activated protein kinase (MAPK) signaling, the ability of MAPK kinases (MKKs, or MEKs) to recognize their cognate MAPKs is facilitated by a short docking motif (the D-site) in the MKK N terminus, which binds to a complementary region on the MAPK. MAPKs then recognize many of their targets using the same strategy, because many MAPK substrates also contain D-sites. The extent to which docking contributes to the specificity of MAPK transactions is incompletely understood. Here we characterize the selectivity of the interaction between MKK-derived D-sites and MAPKs by measuring the ability of D-site peptides to inhibit MAPK-mediated phosphorylation of D-site-containing substrates. We find that all MKK D-sites bind better to their cognate MAPKs than they do to non-cognate MAPKs. For instance, the MKK3 D-site peptide, which is a remarkably potent inhibitor of p38alpha (IC(50) < 10 nm), does not inhibit JNK1 or JNK2. Likewise, MAPKs generally bind as well or better to cognate D-sites than to non-cognate D-sites. For instance, JNK1 and JNK2 do not appreciably bind to any D-sites other than their cognate D-sites from MKK4 and MKK7. In general, cognate, within-pathway interactions are preferred about an order of magnitude over non-cognate interactions. However, the selectivity of MAPKs and their cognate MKK-derived D-sites for each other is limited in some cases; in particular, ERK2 is not very selective. We conclude that MAPK-docking sites in MAPK kinases bind selectively to their cognate MAPKs.
authors.affiliation: Department of Developmental and Cell Biology, University of California, Irvine, CA 92697-2300, USA.
authors.forename: A Jane
authors.initials: AJ
authors.lastname: Bardwell
authors.forename: Erlynn
authors.initials: E
authors.lastname: Frankson
authors.forename: Lee
authors.initials: L
authors.lastname: Bardwell
mesh_terms: D051698:Activating Transcription Factor 2 / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D026161:MADS Domain Proteins / Q000378:metabolism; D048371:MAP Kinase Kinase 3 / Q000378:metabolism; D048669:MAP Kinase Kinase 6 / Q000378:metabolism; D064326:MEF2 Transcription Factors; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048056:Mitogen-Activated Protein Kinase 9 / Q000037:antagonists & inhibitors / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases / Q000737:chemistry* / Q000378:metabolism*; D018006:Myogenic Regulatory Factors / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D013379:Substrate Specificity; D050807:ets-Domain Protein Elk-1 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D026161:MADS Domain Proteins; D064326:MEF2 Transcription Factors; C578035:MEF2A protein, human; D018006:Myogenic Regulatory Factors; D050807:ets-Domain Protein Elk-1; D048056:Mitogen-Activated Protein Kinase 9; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048055:Mitogen-Activated Protein Kinase 8; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; D048669:MAP Kinase Kinase 6; C482530:MAP2K3 protein, human; C482566:MAP2K6 protein, human; D020929:Mitogen-Activated Protein Kinase Kinases