Definition of the human mitochondrial TOM interactome reveals TRABD as a new interacting protein.
The mitochondrial proteome arises from dual genetic origins. Nuclear-encoded proteins need to be transported across or inserted into two distinguished membranes, and the translocase of the outer mitochondrial membrane (TOM) complex represents the main translocase in the outer mitochondrial membrane. Its composition and regulation have been extensively investigated within yeast cells. However, we have little knowledge of the TOM complex composition within human cells. Here, we have defined the TOM interactome in a comprehensive manner using biochemical approaches to isolate the TOM complex in combination with quantitative mass spectrometry analyses. With these studies, we defined the pleiotropic nature of the human TOM complex, including new interactors, such as TRABD. Our studies provide a framework to understand the various biogenesis pathways that merge at the TOM complex within human cells.