The present invention provides a method for detecting interactions between or with any two of at least three target substrates, or any two of at least three features of a target substrate, or a combination of interactions and features of target substrates, by a multiplexed proximity ligation assay, said method comprising: a) for each of the at least three target substrates or features, providing a proximity probe comprising a binding moiety with affinity for the feature or binding site on said substrate, and a proximity probe oligonucleotide coupled on the binding moiety; wherein each of the proximity probe oligonucleotide carries a unique tag sequence; b) mixing the proximity probes with a sample, under a condition to allow binding of each proximity probe to its respective binding site or feature on each of said substrates through the binding moiety, c) simultaneous with, or following step b), forming circularized DNA molecules where any two proximity probes bind sufficiently close to each other on the substrate, wherein each of the circularized DNA molecules comprise complementary sequences to the unique tag sequences from the two proximity probes oligo-nucleotides; d) amplifying the circularized DNA; and e) characterizing the amplified DNA.
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