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Updated: Apr 16, 2026
Identification of Protein Interacting Partners Using Tandem Affinity Purification
Published on: February 25, 2012
Development of a tandem affinity phosphoproteomic method with motif selectivity and its application in analysis of
Laura E Herring1, Kyle G Grant2, Kevin Blackburn1
1Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, NC 27695-7622, United States.
Abstract:
Phosphorylation is an important post-translational modification that is involved in regulating many signaling pathways. Of particular interest are the growth factor mediated Ras and phosphoinositide 3-kinase (PI3K) signaling pathways which, if misregulated, can contribute to the progression of cancer. Phosphoproteomic methods have been developed to study regulation of signaling pathways; however, due to the low stoichiometry of phosphorylation, understanding these pathways is still a challenge. In this study, we have developed a multi-dimensional method incorporating electrostatic repulsion-hydrophilic interaction chromatography (ERLIC) with tandem IMAC/TiO2 enrichment for subsequent phosphopeptide identification by LC/MS/MS. We applied this method to PDGF-stimulated NIH 3T3 cells to provide over 11,000 unique phosphopeptide identifications. Upon motif analysis, IMAC was found to enrich for basophilic kinase substrates while the subsequent TiO2 step enriched for acidophilic kinase substrates, suggesting that both enrichment methods are necessary to capture the full complement of kinase substrates. Biological functions that were over-represented at each PDGF stimulation time point, together with the phosphorylation dynamics of several phosphopeptides containing known kinase phosphorylation sites, illustrate the feasibility of this approach in quantitative phosphoproteomic studies.
Insights
Researchers developed a new phosphoproteomic method combining ERLIC with IMAC/TiO2 enrichment. This approach successfully identified over 11,000 phosphopeptides in PDGF-stimulated cells, advancing cancer signaling pathway research.
Area of Science:
- Biochemistry
- Cell Biology
- Proteomics
Background:
- Phosphorylation is a key post-translational modification regulating crucial signaling pathways.
- Dysregulation of pathways like Ras and phosphoinositide 3-kinase (PI3K) is linked to cancer progression.
- Low stoichiometry of phosphorylation presents a challenge for studying these signaling pathways.
Purpose of the Study:
- To develop and validate a novel multi-dimensional phosphoproteomic method for enhanced phosphopeptide identification.
- To apply the method to PDGF-stimulated NIH 3T3 cells for quantitative analysis of signaling dynamics.
- To investigate the complementary enrichment capabilities of IMAC and TiO2 for kinase substrate identification.
Main Methods:
- Developed a multi-dimensional strategy using electrostatic repulsion-hydrophilic interaction chromatography (ERLIC).
- Incorporated tandem Immobilized Metal Affinity Chromatography (IMAC) and Titanium Dioxide (TiO2) enrichment.
- Utilized Liquid Chromatography-Tandem Mass Spectrometry (LC/MS/MS) for phosphopeptide identification.
Main Results:
- Identified over 11,000 unique phosphopeptides in PDGF-stimulated NIH 3T3 cells.
- Motif analysis revealed IMAC enriches basophilic kinase substrates, while TiO2 enriches acidophilic substrates.
- Demonstrated the feasibility of the method for quantitative phosphoproteomic studies through functional enrichment and dynamic phosphorylation analysis.
Conclusions:
- The developed ERLIC combined with tandem IMAC/TiO2 enrichment is effective for comprehensive phosphoproteomic analysis.
- Sequential enrichment using IMAC and TiO2 is crucial for capturing diverse kinase substrates.
- This method provides valuable insights into signaling pathway regulation and dynamics in response to growth factors.
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