Ligand-induced transmembrane conformational coupling in monomeric EGFR.

Area of Science:

• Molecular Biology
• Biophysics
• Cell Signaling

Background:

• Single-pass cell surface receptors transmit signals across the plasma membrane.
• Ligand binding to monomeric receptors initiates transmembrane signaling.
• Isolating monomeric receptor contributions to signaling is complex.

Purpose of the Study:

• To investigate conformational changes in monomeric epidermal growth factor receptor (EGFR) upon ligand binding.
• To establish extracellular/intracellular conformational coupling within a single receptor molecule.
• To explore the mechanism linking extracellular and intracellular regions in monomeric EGFR.

Main Methods:

• Cell-free expression to produce membrane nanodiscs.
• Single-molecule Förster Resonance Energy Transfer (smFRET) measurements.
• Molecular dynamics simulations.

Main Results:

• Ligand binding induces intracellular conformational changes in monomeric EGFR.
• Demonstrated extracellular/intracellular conformational coupling within a single receptor.
• Electrostatic interactions mediate coupling, inhibited by therapeutics and mutations affecting phosphorylation.

Conclusions:

• A facile mechanism links extracellular and intracellular regions via the transmembrane helix of monomeric EGFR.
• Intramolecular transmembrane conformational changes upon ligand binding may be common in single-pass membrane proteins.
• Findings provide insights into EGFR signaling and transmembrane protein mechanisms.