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 translocation pore. Forms part of the preprotein translocase complex of the outer mitochondrial membrane (TOM complex) which consists of at least 6 different proteins (TOM5, TOM6, TOM7, TOM20, TOM22/TOM9 and TOM40). A number of isoforms are produced. According to EST sequences. Barely detected in roots. No visible phenotype. There are four genes (TOM20-1, TOM20-2, TOM20-3 and TOM20-4) which encode mitochondrial import receptor subunits TOM20, but TOM20-1 is the only one that has not been directly identified in isolated mitochondria from cv. Columbia. In mammals and fungi, the transmembrane domain is located at the N-terminus while it is located at the C-terminus in plants. The overall orientation of the protein in the membrane is therefore inverted. Belongs to the Tom20 family.