Investigating Protein Interactions in Single Cells by Proximity Ligation Assay (PLA)

Many cellular processes are governed by protein-protein interactions. To better understand these processes, it is necessary to understand how different proteins interact under different conditions. Proximity ligation assay (PLA) enables identification of proteins within 40 nm of one another, suggesting interaction, while also providing information on sub-cellular localization of the interaction. This information is particularly informative when monitoring the localization and interaction of transcription factors and other nuclear proteins. Here, we describe an optimized protocol for PLA in mouse embryonic stem cells, trophoblast stem cells, and blastocysts, alongside a demonstration of a robust positive control for nuclear proteins.