Intracellular proteome compartmentalization: a biotin ligase-based proximity labeling approach

Specialized biological processes occur in different regions and organelles of the cell. Additionally, the function of proteins correlate greatly with their interactions and subcellular localization. Understanding the mechanism underlying the specialized functions of cellular structures therefore requires a detailed identification of proteins within spatially defined domains of the cell. Furthermore, the identification of interacting proteins is also crucial for the elucidation of the underlying mechanism of complex cellular processes. Mass spectrometry methods have been utilized systematically for the characterization of the proteome of isolated organelles and protein interactors purified through affinity pull-down or following crosslinking. However, the available methods of purification have limited these approaches, as it is difficult to derive intact organelles of high purity in many circumstances. Furthermore, contamination that leads to the identification of false positive is widespread even when purification is possible. Here, we present a highlight of the BioID proximity labeling approach which has been used to effectively characterize the proteomic composition of several cellular compartments. In addition, an observed limitation of this method based on proteomic spatiotemporal dynamics, was also discussed.