Arminja N Kettenbach, Devin K Schweppe, Brendan K Faherty, Dov Pechenick, Alexandre A Pletnev, and Scott A Gerber. 2011. “Quantitative phosphoproteomics identifies substrates and functional modules of Aurora and Polo-like kinase activities in mitotic cells.” Sci Signal, 4, 179, Pp. rs5.Abstract
Mitosis is a process involving a complex series of events that require careful coordination. Protein phosphorylation by a small number of kinases, in particular Aurora A, Aurora B, the cyclin-dependent kinase-cyclin complex Cdk1/cyclinB, and Polo-like kinase 1 (Plk1), orchestrates almost every step of cell division, from entry into mitosis to cytokinesis. To discover more about the functions of Aurora A, Aurora B, and kinases of the Plk family, we mapped mitotic phosphorylation sites to these kinases through the combined use of quantitative phosphoproteomics and selective targeting of kinase activities by small-molecule inhibitors. Using this integrated approach, we connected 778 phosphorylation sites on 562 proteins with these enzymes in cells arrested in mitosis. By connecting the kinases to protein complexes, we associated these kinases with functional modules. In addition to predicting previously unknown functions, this work establishes additional substrate-recognition motifs for these kinases and provides an analytical template for further use in dissecting kinase signaling events in other areas of cellular signaling and systems biology.
Naushaba Nayeem, Yihong Zhang, Devin K Schweppe, Dean R Madden, and Tim Green. 2009. “A nondesensitizing kainate receptor point mutant.” Mol Pharmacol, 76, 3, Pp. 534-42.Abstract
Ionotropic glutamate receptor (iGluR) desensitization can be modulated by mutations that change the stability of a dimer formed by the agonist binding domain. Desensitization of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors can be blocked by a single point mutation (e.g., GluR2 L483Y) that stabilizes this dimer in an active conformation. In contrast, desensitization of kainate receptors can be slowed, but not blocked, by similar dimer interface mutations. Only covalent cross-linking via introduced disulfides has been previously shown to block kainate receptor desensitization completely. We have now identified an apparently nondesensitizing GluR6 point mutant (D776K) located at the apex of the ligand binding (S1S2) domain dimer interface. Asp776 is one of a cluster of four charged residues in this region that together mediate direct dimer interactions and contribute to the binding sites for one chloride and two sodium ions. Despite the localized +4 change in the net charge of the S1S2 dimer, the D776K mutation actually increased the thermodynamic stability of the dimer. Unlike GluR6 wild type, the D776K mutant is insensitive to external cations but retains sensitivity to external anions. We therefore hypothesize that the unexpected phenotype of this charge reversal mutation results from the substitution of the sodium ions bound within the dimer interface by the introduced lysine NH(3)(+) groups. The nondesensitizing D776K mutant provides insights into kainate receptor gating and represents a potentially useful new tool for dissecting kainate receptor function.