Biology > Study Notes > Southern Methodist University - BIOL 3350chapter 15 cell bio Protein translocators: (All)

Southern Methodist University - BIOL 3350chapter 15 cell bio Protein translocators:

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Protein translocators: - imported mitochondria and chloroplast proteins o most have a signal sequence at the N-terminal that allows them to enter a specific organelle. o Proteins destined for eith... er organelle are translocated simultaneously across both inner and outer membranes as specializes sites where the two membranes contact each other. o Each protein is unfolded as it is transported and its signal sequence is removed after translocation is complete. o Chaperone proteins- also assist in pulling the protein across the two membranes and fold it back once it is inside. o The insertion of the transmembrane proteins into the inner membrane is guided by signal sequences in the protein that start and stop the transfer across the membrane like the insertion for proteins in the ER membrane. Mitochondrial protein translocator process: 1. the mitochondrial signal sequence on a mitochondrial protein is recognized by a receptor on the outer mito membrane. 2. This receptor is associated with a protein translocator a. This complex diffuses laterally in the outer membrane until it encounters the inner membrane translocator. 3. The two translocators then transport the protein across both membranes unfolding the protein in the process. 4. The signal sequence is finally cleaved off by signal peptidase in the mitochondrial matrix. Same process for chloroplasts and the chaperone proteins pull the protein across membranes and help refold [Show More]

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