A protein that is about to be degraded has copies of the protein ubiquitin attached to it by enzymes that add ubiquitin. This enzyme tags the protein that is being degraded to notify the cell that it needs to be degraded. The tagged proteins are sucked into a proteasome, this 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 free amino