Label-Free Single-Molecule Pulldown for the Detection of Released Cellular Protein Complexes

Area of Science:

• Biophysics
• Molecular Biology
• Cellular Signaling

Background:

• Precise detection of intracellular proteins and complexes is crucial for understanding cell signaling and function.
• Existing methods often require labels or large sample amounts, limiting sensitivity and throughput.

Purpose of the Study:

• To present a novel label-free single-molecule pulldown (LFSMP) technique.
• To demonstrate LFSMP's capability for sensitive imaging and kinetic analysis of cellular proteins and complexes.
• To showcase LFSMP's application in studying signaling pathway phosphorylation and improving pulldown specificity.

Main Methods:

• Developed and applied the label-free single-molecule pulldown (LFSMP) technique.
• Utilized plasmonic scattering imaging for label-free detection of surface-captured molecules.
• Quantified binding kinetics and analyzed protein complex phosphorylation.

Main Results:

• Achieved single-molecule sensitivity with low sample consumption (few cells per mm²).
• Demonstrated direct imaging and kinetic quantification of released proteins and complexes.
• Showcased improved pulldown specificity through kinetic analysis.

Conclusions:

• LFSMP offers a sensitive, label-free approach for studying proteins and complexes at the single-molecule level.
• The technique enables detailed kinetic analysis of molecular interactions in signaling pathways.
• LFSMP has the potential to advance the understanding of cellular mechanisms with high resolution.