We have established a broad range of quantitative MS assays for the unbiased analysis of protein-protein interactions and their temporal dynamics. Our BioID/ Turbo-ID assays rely on the fusion of a protein of interest (bait) with a promiscuous biotin ligase enzyme, known as BirA*. Upon expression in living cells, this fusion protein biotinylates proximal proteins within a radius of 10-20 nanometers, covalently attaching biotin molecules to lysine residues. Subsequently, biotinylated proteins are isolated using streptavidin affinity purification, followed by elution and identification via mass spectrometry. By capturing proteins that come into close proximity with the bait protein, the BioID assay provides a comprehensive snapshot of the protein interactome within the cellular context.