A dynamic machinery for import of mitochondrial precursor proteins

Abstract 

Mitochondria contain ∼1000 different proteins, which are located in four different compartments, outer membrane, inner membrane, intermembrane space and matrix. The vast majority of these proteins has to be imported from the cytosol. Therefore, sophisticated molecular machineries have evolved that mediate protein translocation across or insertion into mitochondrial membranes and subsequent assembly into multi-subunit complexes. While the initial entry of virtually all mitochondrial proteins is mediated by the general import pore of the outer membrane, at least four different downstream pathways are dedicated to import and assembly of proteins into a specific compartment.

Abbreviations: GIP, general import pore, MIA, mitochondrial intermembrane space import and assembly, PAM, presequence translocase-associated motor, SAM, sorting and assembly machinery, TIM, translocase of inner membrane, TOM, translocase of outer membrane

Keywords: Mitochondria, Protein import, Sorting and assembly, Translocase of inner membrane complex, Presequence translocase-associated motor complex, Mitochondrial intermembrane space import and assembly pathway