Quantitation of Met tyrosine phosphorylation using MRM-MS

Area of Science:

• Biochemistry
• Cell Biology
• Proteomics

Background:

• Phosphorylation is a critical regulator of cellular signaling pathways.
• Measuring phosphorylation occupancy, especially at closely located sites, is challenging.
• Multiple-reaction monitoring mass spectrometry (MRM-MS) offers advanced quantitative capabilities.

Purpose of the Study:

• To develop and validate a targeted quantitation approach for measuring absolute phosphorylation occupancy.
• To quantify the phosphorylation status of Y1234 and Y1235 sites on Met.
• To apply this method to assess Met phosphorylation in cells treated with a Met inhibitor.

Main Methods:

• Development of a targeted quantitation strategy using MRM-MS.
• Absolute quantification of phosphorylation occupancy at Met Y1234 and Y1235 in recombinant Met.
• Application of the method to SNU-5 cells treated with a Met inhibitor.

Main Results:

• The developed MRM-MS approach successfully measured absolute phosphorylation occupancy at Met Y1234 and Y1235.
• Absolute phosphorylation occupancy was determined for recombinant Met.
• The method was applied to quantify changes in Met phosphorylation in response to inhibitor treatment in SNU-5 cells.

Conclusions:

• A robust method for absolute phosphorylation site quantitation using MRM-MS has been established.
• This approach enables precise measurement of phosphorylation dynamics at key signaling nodes like Met.
• The technique is valuable for studying Met signaling and evaluating Met inhibitors in cellular contexts.