Component of the TOM (translocase of outer membrane) receptor complex responsible for the recognition and translocation of cytosolically synthesized mitochondrial preproteins. Together with TOM20 and TOM22 functions as the transit peptide receptor at the surface of the mitochondrion outer membrane and facilitates the movement of preproteins into the TOM40 translocation pore. Forms part of the TOM (translocase of outer membrane) complex that consists of at least 7 different proteins (TOM5, TOM6, TOM7, TOM20, TOM22, TOM40 and TOM70). In the complex interacts with TOM22. Interacts with TOM37. Present with 45300 molecules/cell in log phase SD medium. Belongs to the Tom70 family.