For reference, see Voet & Voet Biochemistry / Figure 11-78
Original manuscript: The TOM core complex: The general protein import pore of the outer membrane of mitochondria. Ahting, U., Thun, C., Hegerl, R., Typke, D., Nargang, F.E., Neupert, W., & Nussberger, S. J. Cell Biol. 147, 959-968 (1999) (Cover article)