Abstract
Protein phosphorylation is a dominant mechanism of information transfer in cells, and a major goal of current proteomic efforts is to generate a system-level map describing all the sites of protein phosphorylation. Recent efforts have focused on developing technologies for enriching and quantifying phosphopeptides. Identification of the sites of phosphorylation typically relies on tandem mass spectrometry to sequence individual peptides. Here we describe an approach for phosphopeptide mapping that makes it possible to interrogate a protein sequence directly with a protease that recognizes sites of phosphorylation. The key to this approach is the selective chemical transformation of phosphoserine and phosphothreonine residues into lysine analogs (aminoethylcysteine and beta-methylaminoethylcysteine, respectively). Aminoethylcysteine-modified peptides are then cleaved with a lysine-specific protease to map sites of phosphorylation. A blocking step enables single-site cleavage, and adaptation of this reaction to the solid phase facilitates phosphopeptide enrichment and modification in one step.
Publication types
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Evaluation Study
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Cyclic AMP-Dependent Protein Kinases / analysis
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Cyclic AMP-Dependent Protein Kinases / chemistry
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Endopeptidases / chemistry*
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Endopeptidases / metabolism
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Enzyme-Linked Immunosorbent Assay / methods
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Peptide Hydrolases / chemistry*
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Peptide Hydrolases / metabolism
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Phosphoamino Acids / chemistry*
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Phosphoamino Acids / metabolism
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Phosphopeptides / analysis
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Phosphopeptides / chemistry*
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Phosphopeptides / metabolism
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Phosphorylation
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Phosphoserine / chemistry
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Phosphoserine / metabolism
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Phosphothreonine / chemistry
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Phosphothreonine / metabolism
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Phosphotransferases / chemistry*
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Phosphotransferases / metabolism
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Protein Interaction Mapping / methods*
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Proteome / analysis
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Proteome / chemistry
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Proteome / metabolism
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Proteomics / methods*
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Tubulin / analysis
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Tubulin / chemistry
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Tubulin / metabolism
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beta-Adrenergic Receptor Kinases
Substances
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Phosphoamino Acids
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Phosphopeptides
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Proteome
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Tubulin
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Phosphothreonine
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Phosphoserine
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Phosphotransferases
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Cyclic AMP-Dependent Protein Kinases
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beta-Adrenergic Receptor Kinases
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Endopeptidases
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Peptide Hydrolases