Identifying and quantifying two ligand-binding sites while imaging native human membrane receptors by AFM

Area of Science:

• Biophysics
• Cell Biology
• Nanotechnology

Background:

• Imaging cell membrane receptors and their ligand interactions is crucial in life sciences.
• Existing nanoscopic methods are insufficient for detailed characterization of these interactions.
• Human protease-activated receptors (PAR1) play vital roles in cellular processes.

Purpose of the Study:

• To develop a nanoscopic method for imaging cell membrane receptors and their ligand interactions.
• To simultaneously localize and quantify the binding of multiple ligands to PAR1.
• To overcome limitations of current nanoscopic techniques in receptor-ligand studies.

Main Methods:

• Multifunctional high-resolution atomic force microscopy (AFM) was employed.
• AFM tips were bifunctionalized with a native receptor-activating peptide and a tris-N-nitrilotriacetic acid (tris-NTA) group.
• A His10-tag engineered to PAR1 facilitated binding to the tris-NTA group.

Main Results:

• The study successfully imaged native PAR1 in lipid membranes at high resolution.
• Simultaneous localization and quantification of binding for two different ligands to PAR1 were achieved.
• The method allows differentiation of ligand binding to distinct receptor sites.

Conclusions:

• The developed AFM method provides a powerful tool for studying receptor-ligand interactions at single-receptor resolution.
• This technique is applicable to various biological systems, both in vitro and in vivo.
• It enables concurrent detection and localization of multiple ligand-binding sites on receptors.