Coincidence detection

Abstract

The invention relates to a method of detecting the coincidence of two biomolecular structures in a solid phase sample, said method comprising: (i) providing a first and a second fusion protein, each fusion protein comprising (a) a detection domain, said detection domain comprising a DNA binding domain; said detection domain capable of binding a cognate specific nucleotide sequence in co-operation with a further detection domain; (b) a recognition domain, said recognition domain capable of binding a target biomolecular structure; and (c) a connector domain; said connector domain being fused at one end to the detection domain and being fused at the other end to the recognition domain; wherein at least two of (a), (b) and (c) are heterologous to one another; wherein the recognition domains of said first and said second fusion proteins are capable of binding to first and second biomolecular structures; (ii) contacting the sample with said first and second fusion proteins; (iii) incubating to allow binding; (iv) removing unbound fusion protein; (v) contacting the sample with nucleic acid comprising said cognate specific nucleotide sequence; (vi) incubating to allow heterotrimeric binding of the nucleic acid; (vii) detecting nucleic acid bound to the sample wherein detection of nucleic acid in step; (vii) indicates that the two biomolecular structures are present coincidentally in said sample.