Detection of ligand–receptor binding using microfluidic frontal affinity chromatography on proteoliposomes derived directly from native cell membranes

• A microfluidic frontal affinity chromatography setup coupled to MS is described.
• We study interactions between ligands and the GPCR receptor Ste2 in yeast.
• Ranking of binding affinity for the α-factor and analog ligands is demonstrated.

A method for characterization of ligand binding to membrane receptors in their native cell membrane is presented. The methodology is based on microfluidic frontal affinity chromatography coupled to mass spectrometry (FAC-MS). Proteoliposomes with receptor of interest are prepared directly from cell membranes and serve as a stationary phase in a microfluidic flow cell for frontal analysis. The G-Protein-Coupled Receptor (GPCR) Ste2 involved in the pheromone-induced yeast mating pathway is used as a model receptor for proof of principle characterization. The ligand affinity of the natural pheromone peptide, the α-factor, is compared to a set of pheromone analogs having different receptor affinities. With short preparation time, preserved lipid composition and the ability to immobilize proteoliposomes from any cell membrane, we propose that our methodology with immobilized proteoliposomes together with microfluidics FAC-MS can be an important improvement for ligand-receptor studies in native membranes.