Central component of the receptor complex responsible for the recognition and translocation of cytosolically synthesized mitochondrial preproteins. Together with 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 (By similarity). Required for the translocation across the mitochondrial outer membrane of cytochrome P450 monooxygenases. Forms part of the preprotein translocase complex of the outer mitochondrial membrane (TOM complex) which consists of at least 7 different proteins (TOMM5, TOMM6, TOMM7, TOMM20, TOMM22, TOMM40 and TOMM70). Interacts with TOM22. Interacts with APEX1 (By similarity). Interacts with TBC1D21 (By similarity). Ubiquitinated by PRKN during mitophagy, leading to its degradation and enhancement of mitophagy. Deubiquitinated by USP30. Belongs to the Tom20 family.