The ubiquitin proteasome system is responsible for degrading faulty and damaged proteins. These protein complexes are found in the nucleus and the cytoplasm in eukaryotes and archaea. The proteasome breaks down proteins into peptides that are seven to eight amino acids long by proteolysis, a type of chemical reaction. In order to enter the proteasome for degradation, proteins first need to be tagged by a small protein called ubiquitin. The ubiquitin is attached by an enzyme called ubiquitin ligase. After one ubiquitin is attached to the molecule, it sends a signal to other ubiquitin ligases to attach more ubiquitin proteins. Once enough ubiquitin has attached to the protein, the proteasome allows the protein to fasten itself to its cap. The cap opens and the unwinding protein is able to enter the catalytic core of the proteasome. The protein is chopped up and released back into the cell to be used again. Occasionally, this system can malfunction, leaving either too much of a faulty protein or breaking down healthy ones. This can cause diseases such as Alzheimer's disease, cancers, rheumatoid arthritis, and many infectious diseases. Recently a new drug has been created called bortezomib. Bortezomib is the first Food and Drug Administration approved proteasome inhibitor drug in the United States. …show more content…
The drug is a dipeptide made up of a pyrazinoic acid, phenylalanine, and leucine with boronic acid. Bortezomib works by inhibiting, or changing, the proteolytic action of the proteasome. The drug turns off the adhesion of multiple myeloma cells and as a result, cancer cells are no longer able to build up in the blood. Also with this drug, the proteasome is no longer able to break down cyclins which are needed to complete mitosis of the cancer cells. Additionally, bortezomib inhibits the gene Bcl-2 which later leads to cell death by