Multiplexed protein detection by proximity ligation for cancer biomarker validation
We present a proximity ligation–based multiplexed protein detection procedure in which several selected proteins can be detected via unique nucleic-acid identifiers and subsequently quantified by real-time PCR. The assay requires a 1-μl sample, has low-femtomolar sensitivity as well as five-log linear range and allows for modular multiplexing without cross-reactivity. The procedure can use a single polyclonal antibody batch for each target protein, simplifying affinity-reagent creation for new biomarker candidates.