Name the different types of machinery for mitochondrial transport.
TOM: translocase of the outer membrane
TIM: translocase of the inner membrane
MIM: mito membrane import
SAM: sorting and assembly machinery
β-barrel insertion
MIA: mitochondrial intermembrane space import and assembly
MPP: mitochondrial processing peptidase
Which kind of signal does the presequence pathway require?
presequence (15-50 aa, amphiphatic alpha-helix)
Describe the presequence pathway. What kind of processing takes place after the import into the matrix?
chaperones recognize presequence
protein is transported to the TOM canal
import
protein can either stay in the intermembrane space or is further transported via
TIM canal with PAM (presequence-translocase associated motor)
Processing
removal of presequence (MPP: mitochondrial processing peptidase)
removal of destabilizing N-terminal amino acid (Icp55, Oct1)
folding (Hsp60)
How are proteins integrated into the mitochondrial membrane?
Presequence pathway
Mgr2, associated with TIM, controls lateral sorting
sorting signal is removed by IMP (inner membrane protease)
What is the Oxidase Assembly Translocase?
co-translational integration of mitochondrial proteins into the inner membrane of the mitochondrium
also responsible for the assembly of TIM
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