One way to define a protein’s purpose is by its protein-protein interactions (PPIs). These interactions are often modeled as binary relationships, i.e. protein A interacts with protein B; but proteins are social biomolecules. They can be part of multiple dynamic and overlapping complexes that have distinct functions. Many existing methods for identifying PPIs, such as affinity purification mass spectrometry (AP-MS), lack the ability to specifically identify proteins that interact with a particular protein complex as opposed to an individual protein. The Bethune Lab has overcome this limitation by creating Split-BioID, a spatiotemporally controllable version of the proximity-dependent biotinylation technique BioID. The key advantage of Split-BioID is that it allows for the validation of a binary PPI as well as the identification of additional interacting factors.