Bio-ID, a proximity-proteomics based technique, tells you which proteins are in the immediate cellular environment of your target molecule.
The Bio-ID method in our proteomics services is a complementary approach to co-IPs, whereby cells are made to synthesise a fusion between a protein of interest and a non-specific biotin ligase, such as BirA R118G, a promiscuous mutant of E. coli BirA. The cells are then pulsed with biotin, which results in the biotinylation of proteins within a ~10 nm sphere around the fusion protein. Biotinylated proteins are then purified using streptavidin beads, digested and peptides analysed by LC-MS/MS
Bio-ID allows the detection of weak interactors of the target protein which may not stay attached during a co-IP, as well as proximal proteins which may be functionally relevant but not interact with the target.
Bio-ID is SILAC compatible:
– Light = beads only
– Medium = BirA R118G transfection
– Heavy = BirA R118G-fusion transfection