A protein that is going to be degraded has copies of the ubiquitin protein attached to it by ubiquitin-adding enzymes. This enzyme marks the protein that is being degraded to inform the cell that it needs to be degraded. The labeled proteins are sucked into a proteasome, it is a protein based component, inside the proteasome, and the protein it has ingested is digested into small peptide fragments, these fragments are then released into the cytoplasm where other proteases digest it further until it is digested. becomes a free amino