Proteasomes
A Proteasome is a protein complex in cells containing proteases; it breaks down the proteins that have been tagged by ubiquitin. The function of the proteasome is to degrade unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. Proteasomes are protein degradative machines that are found in the nucleus and the cytoplasm. They are not only found in eukaryotic organisms but have also been found in archaebacteria. Proteasomes play many roles in the cells life. The importance of the Proteasome is it's removal of abnormal and misfolded proteins from the cell. It plays a very important role in the immune system by generating antigenic peptides that are presented by the (MHC) - Major Histocompatibility complex class 1 molecules.