Protocol for visualizing conditional interaction between transmembrane and cytoplasmic proteins.

This protocol visualizes dynamic interaction between a transmembrane protein and an intracellular protein induced by clusterization/oligomerization of the transmembrane protein. Association-dissociation of the intracellular region of the transmembrane protein with cytoplasmic protein(s) is detected by proximity ligation assay. Since a transmembrane protein often resists extraction, biochemical analysis of its dynamic interaction with cytoplasmic effectors is cumbersome. This protocol quantitatively visualizes protein-protein interaction occurring in the membrane periphery, providing a powerful tool to elucidate signal transduction across the membrane. For complete details on the use and execution of this protocol, please refer to Ooki et al. (2019).