In mitochondria, proteins accumulate in the:
Mitochondria -
Each mitochondria is a double membrane bound structure with the outer membrane and the inner membrane dividing its lumen distinctly into two aqueous compartments.
It is the site of aerobic respiration. It produces cellular energy in the form of ATP, hence called as 'power house' of the cell.
The inner membrane of mitochondria contain more than 151 different polypeptides and has a very high protein to phospholipid ration.