Proteasomes are protein complexes that degrade unneeded or misfolded proteins by breaking peptide bonds within the protein (proteolysis)

• Proteasomes are used by the cell to help regulate protein expression levels and recycle amino acids

Proteins targeted for degradation by the proteasome are tagged with a small protein called ubiquitin

• The ubiquitinated protein is recognised by an outer regulatory complex that mediates access to a proteolytic core

• The regulatory complex and inner core are separated by an ⍺-subunit that acts as a gate to prevent unnecessary proteolysis

By controlling the breakdown and subsequent synthesis of proteins (through the recycling of amino acids), the proteasome plays an important role in sustaining a functional proteome (the totality of cellular proteins)