Mitochondrial preprotein translocases as dynamic molecular machines

The Tim21 binding domain connects the preprotein translocases of both mitochondrial membranes.

Proteins destined for the mitochondrial matrix are imported by the translocase of the outer membrane--the TOM complex--and the presequence translocase of the inner membrane--the TIM23 complex. At present, there is no structural information on components of the presequence translocase. Tim21, a subunit of the presequence translocase consisting of a membrane anchor and a carboxy-terminal domain e...

Mitochondrial preprotein translocase.

Mitochondria import most of their proteins from the cytosol. Dynamic protein complexes in the mitochondrial outer and inner membranes are responsible for the specific recognition and membrane translocation of preproteins. The preprotein translocase of the outer mitochondrial membrane contains several import receptors and a general import pore. The preprotein translocase of the inner membrane co...

Dynamic Regulation of Function of the Mitochondrial TIM23 Preprotein Translocase

Mechanistic and Functional Studies of Proteins 1019 Protein import into mitochondria

Mitochondria comprise approx. 1000–3000 different proteins, almost all of which must be imported from the cytosol into the organelle. So far, six complex molecular machines, protein translocases, were identified that mediate this process. The TIM23 complex is a major translocase in the inner mitochondrial membrane. It uses two energy sources, namely membrane potential and ATP, to facilitate pre...

The Protein Import Machinery of Mitochondria*

Most mitochondrial proteins are encoded by nuclear genes and then synthesized as precursors on cytosolic ribosomes after which they must be imported into the organelle. The mitochondrial membranes contain specific machineries (translocases) for recognition, translocation, and membrane insertion of precursor proteins. In recent years, important progress has been made in characterizing the molecu...