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Updated: May 29, 2025
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Resin-Assisted Capture Coupled with Isobaric Tandem Mass Tag Labeling for Multiplexed Quantification of Protein Thiol Oxidation
Published on: June 21, 2021
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Searching for Sulfotyrosines (sY) in a HA(pY)STACK.
Jordan Tzvetkov1, Claire E Eyers2,3, Patrick A Eyers3
1Computational Biology Facility, University of Liverpool, Crown Street, Liverpool L69 7ZB, U.K.
Journal of Proteome Research
|February 5, 2025
Summary
Tyrosine sulfation (sY) is often mistaken for tyrosine phosphorylation (pY) in mass spectrometry. This study found that while misidentification can occur, it is rare in high-quality phosphoproteomics data.
Area of Science:
- Biochemistry
- Proteomics
- Mass Spectrometry
Background:
- Protein sulfation is vital for protein interactions but is understudied.
- Sulfation and phosphorylation are isobaric, complicating mass spectrometry analysis.
- The extent of tyrosine sulfation (sY) misidentification as tyrosine phosphorylation (pY) is a concern.
Purpose of the Study:
- To investigate the frequency of sY misidentification in human phosphoproteomics data.
- To differentiate between sY and pY using mass spectrometry.
- To identify novel sY sites.
Main Methods:
- Screened ~45 million peptide-spectrum matches (PSMs) from the PeptideAtlas human phosphoproteome.
- Utilized Gaussian mixture models (GMMs) to detect mass error shifts indicative of sulfation.
- Applied manual annotation for false positive filtering.
Main Results:
- Identified 104 candidate sulfated peptidoforms.
- Confirmed 31 convincing peptidoforms, including 7 novel sY sites.
- Provided strong evidence for sY at Y47 in calumenin.
Conclusions:
- Misidentification of sY in phosphoproteomics data is relatively rare.
- Sulfation is unlikely to be a significant confounding factor in high-quality phosphoproteomics datasets.
- This study enhances the accuracy of phosphoproteomics and sulfation site identification.
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