Biotinylation protein is one technique used in biotechnology for tagging the proteins.
In BioID, the protein of interest is fused to a “promiscuous” biotin ligase and stably expressed in cells; the fusion protein biotinylated proximal proteins only when excess biotin is added to the medium. High-affinity avidin/streptavidin-beads are used to capture biotinylated candidates in a single step.