Measuring molecular interaction of integral membrane proteins is critical for understanding cellular functions, validating biomarkers and screening drugs. Despite the importance, developing such a capability has been a difficult challenge, especially for small molecules binding to membrane proteins in their native cellular environment. Here we show that the binding of both large and small molecules to membrane proteins can be quantified on single cells by trapping single cells with a microfluidic device, and detecting molecular binding-induced cellular membrane deformation on nanometer-scale with label-free optical imaging. We studied the molecular interactions of four major types of membrane proteins, including glycoproteins, ion channels, G-protein coupled and tyrosine kinase receptors. The single cell detection capability reveals the importance of local membrane environment on molecular binding, and variability in the binding kinetics of different cell lines, and heterogeneity of different cells within the same cell line.

Label-free quantification of small molecule interactions with membrane proteins in single cells by mechanical amplification

2019 Spring National Meeting

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