Proximity ligation assay and its applications

Abstract

Proximity Ligation Assay (PLA) is a powerful tool for studying protein-protein interactions and in situ analysis of protein localization in specific cells or tissues. To identify and measure target protein interactions in cells or tissues, PLA combines the specificity of immunofluorescence with the sensitivity of polymerase chain reaction (PCR). The assay is based on the principle that, when two antibodies specific for different epitopes of a target protein are brought into close proximity, they can form a stable protein complex that can be detected by ligation of two oligonucleotides conjugated to the antibodies. The ligation product can then be amplified by PCR and visualized by fluorescence or confocal microscopy. PLA has several advantages over other methods for detecting protein interactions, such as immunofluorescence, co-immunoprecipitation, FRET/BRET, immunoelectron microscopy. Unlike these methods, PLA can detect low-abundance or transient interactions and any In vitro protein purification. In addition, PLA can be combined with other techniques like electron microscopy to visualize subcellular localization of proteins in the cell organelles. PLA is a versatile and sensitive tool for studying protein localization in medical diagnostics.