The Ubiquitin Proteasome System (UPS) is a cellular mechanism that regulates protein degradation. It tags unwanted or damaged proteins with a small protein called ubiquitin, marking them for destruction. This process is essential for maintaining cellular health and function by removing proteins that are no longer needed or are malfunctioning. Once tagged, these proteins are directed to the proteasome, a large protein complex that breaks them down into smaller peptides. This degradation process recycles amino acids for new protein synthesis and helps control various cellular processes, including the cell cycle, signaling, and responses to stress.