protein targeting to mitochondrial matrix

Question 1

presequence

Answer 1

protein containing the mitochondrial targeting sequence

Question 2

where is the presequence synthesized?

Answer 2

entirely in the cytoplasm

Question 3

The presequence is always located at the and contains how many AA

Answer 3

N terminus of the protein and contains 15-50 AA

Question 4

As it emerges from the ribosome during translation, the presequence coils into an

Answer 4

amphipathic alpha helix

Question 5

What is an amphipathic alpha helix?

Answer 5

one side is polar, other side is nonpolar (acts as a 3D key)

Question 6

What does the presequence bind to and where?

Answer 6

receptor on the outer mitochondrial membrane

Question 7

What do chaperones do?

Answer 7

help maintain the protein in an unfolded state until it can be transported into the mitochondria

Question 8

The protein is moved across the outer membrane, and then the inner membrane, through a pair of

Answer 8

translocation channels

Question 9

Does this process require energy?

Answer 9

Yes- A combination of ATP hydrolysis and harnessing the energy already stored in the proton gradient across the inner mitochondrial membrane is used to drive protein import.

Question 10

Chaperones assist with…

Answer 10

keeping the protein unfolded on the outside of the mitochondria, pulling the protein through the channel, and then folding the protein on the inside of the mitochondria.

Question 11

Once the protein is inside the matrix of the mitochondria, the …. by a proteolytic enzyme known as the….

Answer 11

presequence is removed ; mitochondrial processing peptidase, or MPP

Question 12

After the presequence is removed

Answer 12

the protein is further processed and folded into its final mature shape.