Regulation of the protein entry gate assembly by mitochondrial porin.

Mitochondrial biogenesis and functions rely on transport of their resident proteins as well as small molecules/ions across their membranes. The TOM complex functions as a protein entry gate for most mitochondrial proteins and mitochondrial porin facilitates transport of small-molecule metabolites and ions. We recently found a novel role of porin in regulation of the TOM complex assembly, the dynamic exchange between the dimer and trimer, and different substrate specificities of the dimer and trimer. Using distinct assembly forms customized for different client proteins, the TOM complex can handle ~ 1000 different mitochondrial protein for their import into mitochondria.