Pg 713-716.docx

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11 Apr 2012
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Pg. 713-716
The Transport of Proteins into Mitochondria and chloroplasts
Mitochondria and chloroplasts are double membrane organelles
Can synthesize ATP
Both contain own DNA, ribosomes and chloroplasts
Both can synthesize their own proteins
Mitochondrion has two sub compartments: matrix and intermembrane
space
The compartments come together to form inner membrane
The inner membrane is enclosed by cristae and an outer membrane which
surrounds the cytosol
Chloroplasts have the same two sub compartments; but it has thylakoid
space and thylakoid space
Protein Translocation: process of protein movement
Translocation into Mitochondria Depends on Signal Sequences and Protein
Translocators
Proteins imported in the mitochondria taken up by the cytosol and release of
ribosomes occurs within a few mins
Mitochondrial precursor proteins: synthesize mitochondrial proteins
The proteins contain signal have signals that direct the protein to the correct
mitochondrial compartment
The proteins all form an alpha helix
Protein translocators: mediate protein translocation across the
mitochondrial membrane
TOM complexes: transfer proteins from outer membrane
TIM complexes: transfer proteins from inner membrane
Complexes contain some compartments are receptors and others as channels
SAM complex: helps the protein fold properly in the outer matrix
OXA complex: helps insert the inner membrane proteins properly
Mitochondrial Precursor Proteins are Imported ad Unfolded Polypeptide Chain
Mitochondrial precursor proteins cannot be folded by themselves they need
the help of chaperone proteins (Hsp 70)