Sensitive and Accurate Quantitation of Phosphopeptides Using TMT Isobaric Labeling Technique

Area of Science:

• Proteomics
• Cellular signaling
• Post-translational modifications

Background:

• Phosphorylation is crucial for protein function and signal transduction.
• Mass spectrometry (MS) with isobaric tandem mass tags (TMTs) enables large-scale phosphoproteome analysis.
• Current MS3-based methods (e.g., Synchronous Precursor Selection) face challenges with phosphopeptide identification rates and quantitation accuracy in complex samples.

Purpose of the Study:

• To develop and optimize novel acquisition methods for TMT-labeled phosphoproteome analysis.
• To enhance phosphopeptide identification rates and minimize ratio distortion in quantitative proteomics.
• To apply improved methods for large-scale phosphoproteomic profiling of cell lines.

Main Methods:

• Development and optimization of two new MS acquisition methods for TMT-labeled phosphoproteome samples.
• Application of these methods to analyze A549 cell lines treated with insulin or insulin growth factor 1 (IGF-1).
• Quantitative analysis of phosphopeptides across 10 samples without prefractionation.

Main Results:

• Achieved higher phosphopeptide identification rates and reduced ratio distortion compared to previous methods.
• Identified 3378 protein groups and 12,465 phosphopeptides, with 10,436 quantified across 10 samples.
• Enabled accurate mapping of numerous signaling pathways, including mTOR, EGFR, and insulin signaling.

Conclusions:

• The developed acquisition methods significantly improve the accuracy and efficiency of TMT-based phosphoproteome analysis.
• These advancements facilitate deeper insights into cellular signaling networks through large-scale phosphopeptide quantitation.
• The study provides a robust platform for investigating phosphorylation dynamics in response to growth factors.