About TOMM / Translocase of Outer Mitochondrial Membrane:
TOMM is a part of the TOM complex, which helps import proteins into mitochondria. TOMM also transports ADP/ATP from matrix to intermembrane space.
TOMM Structure
TOM complexes are found on the outer mitochondrial membrane and translocate solute molecules across the membrane in an ATP-dependent manner. TOMM, together with TOM core complex, forms TOM complex. TOM complex can bind both ADP/ATP and the substrate protein simultaneously via interactions between its subunits TOM20 (TOM5 in yeast) binds tightly with TOM22 (TOM6 in yeast), allowing them to interact stably during their interaction with other TOM components or substrates.
Translocase of Outer Mitochondrial Membrane Mechanism
Tom40 and Tom70 form the pore through which molecules are transported. TOMM is a peripheral membrane protein with three transmembrane domains, which spans the mitochondrial outer membrane. TOMM exists as a dimer in solution, and both subunits contribute to transport activity. TOMM transports ADP/ATP from the matrix to intermembrane space and translocates other proteins across the TOM complex into mitochondria. Although TOMM can mediate solute transport through the TOM complex on its own, it functions synergistically with Tom20 and Tom22.
TOMM Function
Protein that is encoded by DNA that will be used for protein synthesis must reach its destination before being modified. It was initially thought that since mitochondria floated freely within cells surrounded by cytosol, any proteins destined for mitochondria must come from the cytosol. However, this turned out not to be the case; proteins could also reach mitochondria through selective transport. TOMM is involved in particular protein transfer across the TOM complex into mitochondria, and TOMM has been found essential in mediating mitochondrial protein import such as mitofilin, ND6, and Cytochrome c1.