Protein kinases have emerged as attractive targets for treatment of several diseases prompting large-scale phosphoproteomics studies to elucidate their cellular actions and the design of novel inhibitory compounds. Current limitations include extensive reliance on consensus predictions to derive kinase-substrate relationships from phosphoproteomics data and incomplete experimental validation of inhibitors. To overcome these limitations in the case of protein kinase CK2, we employed functional proteomics and chemical genetics to enable identification of physiological CK2 substrates and validation of CK2 inhibitors including TBB and derivatives. By 2D electrophoresis and mass spectrometry, we identified the translational elongation factor EEF1D as a protein exhibiting CK2 inhibitor-dependent decreases in phosphorylation in (32)P-labeled HeLa cells. Direct phosphorylation of EEF1D by CK2 was shown by performing CK2 assays with EEF1D -FLAG from HeLa cells. Dramatic increases in EEF1D phosphorylation following λ-phosphatase treatment and phospho- EEF1D antibody recognizing EEF1D pS162 indicated phosphorylation at the CK2 site in cells. Furthermore, phosphorylation of EEF1D in the presence of TBB or TBBz is restored using CK2 inhibitor-resistant mutants. Collectively, our results demonstrate that EEF1D is a bona fide physiological CK2 substrate for CK2 phosphorylation. Furthermore, this validation strategy could be adaptable to other protein kinases and readily combined with other phosphoproteomic methods.
Pubmed ID: 21936567 RIS Download
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A collection of both commercial and noncommercial software products which includes: Mascot Distiller, Mascot Parser, and Mascot Server. Mascot Distiller is commercial and provides a single interface to process raw data into de-isotoped peak lists. This tool can also be used for the easy distribution of search and quantitative results to colleagues. The non-commercial Mascot Parser software provides an API (Application Programmer Interface) that makes it easier to access search results written in C++, Java, Python and Perl. Mascot Server is non-commercial, and is a collection of peptide mass fingerprints as well as a MS/MS database. A selection of popular sequence databases are available online and include SwissProt, NCBInr, and the EST divisions of EMBL. This server is best used for evaluating and searching for smaller data sets.
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View all literature mentionsA software package and server used to identify and characterize proteins from primary sequence databases using mass spectrometry data. Mascot integrates peptide mass fingerprinting, sequence querying, and MS/MS ion searching in order to search for proteins in databases like SwissProt, NCBInr, EMBL EST divisions, contaminants, and cRAP. If a license is purchased, users may: search data sets that exceed the 1200 spectrum limit of the free version; set up automated, high throughput work; add and edit proteins and quantification methods; and search a preferred collection of sequence databases. The software package works with instruments from AB Sciex, Agilent, Bruker, Jeol, Shimadzu, Thermo Scientific, and Waters.
View all literature mentionsCell line HeLa is a Cancer cell line with a species of origin Homo sapiens
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