Comprehensive insulin receptor phosphorylation dynamics profiled by mass spectrometry.

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Signaling

Background:

• Insulin receptor (IR) phosphorylation is crucial for understanding insulin signaling and its regulation.
• Previous methods identified limited IR phosphorylation sites, necessitating more exhaustive analysis.

Purpose of the Study:

• To conduct the most comprehensive assessment of IR phosphorylation sites and their kinetics.
• To compare the effects of insulin and a novel IR peptide agonist on IR phosphorylation and trafficking.

Main Methods:

• Utilized nano-liquid chromatography-tandem mass spectrometry for exhaustive IR phosphorylation analysis.
• Analyzed 13 IR phosphorylation sites and 22 combinations, including kinetic analysis.
• Performed cell trafficking experiments to assess IR localization with different agonists.

Main Results:

• Identified and analyzed 13 IR phosphorylation sites and 22 combinations, revealing diverse phosphorylation kinetics.
• Observed contrasting phosphorylation dynamics between insulin and the IR peptide agonist.
• Found the IR peptide agonist did not induce IR to the early endosome, likely due to altered phosphorylation.

Conclusions:

• Provides a powerful tool for investigating IR signaling and trafficking.
• Highlights diverse phosphorylation kinetics that differ from expectations for known IR agonists.
• Suggests potential for designing improved IR agonists with enhanced therapeutic utility based on differential phosphorylation.