Abstract

We developed a split proximity circuit (SPC) assay to directly measure interaction events, e.g. drug binding and receptor clustering. The SPC probes are triggered by the dual recognition of target(s) in close proximity, e.g. receptor dimers, to generate an amplified fluorescence signal within 30 minutes. It is a robust platform (z' > 0.8) under isothermal condition and single-step operation. As a proof-of-concept, we demonstrated the use of SPC assay on the human epidermal growth factor receptor (HER) family using different sample formats (purified proteins, cell lysates and on fixed whole cells). We envision that the assay will find greatest utility for mapping interactions of biologics with cell surface receptors in biologically relevant models.