Proximity Ligation Assay

The proximity ligation assay (in situ PLA) is a biochemical method of detecting protein-protein interactions. The PLA is a combination of an ELISA with signal amplification by polymerase chain reaction and therefore related to an immuno- polymerase chain reaction.

Principle

Against both putative interaction partners antibodies of different species are needed. After a bond of two interaction partners together, the detection is performed based on different immunoconjugates. The immunoconjugates have different oligonucleotides which together form a ring after the addition of two adapter oligonucleotides due to the spatial proximity, which is reproduced by ligation in a polymerase chain reaction by rolling circle replication. Thus, interactions of a few molecules can be detected, but antibodies specific for both interaction partners must be present. This requires knowledge of both partners, making the method to confirm the results of other methods used for determining protein - protein interactions. With a fluorescent -labeled hybridization probe can be detected due to the fluorescent staining, compared to the negative controls, with a fluorescent microscope, the interaction in cells and tissue sections.