What is the role of the ubiquitin–proteasome system in protein homeostasis?

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What is the role of the ubiquitin–proteasome system in protein homeostasis?

Protein turnover and quality control are tightly governed by the ubiquitin-proteasome system. It marks target proteins with ubiquitin chains, signaling that they should be degraded by the proteasome. The 26S proteasome recognizes these ubiquitin tags, unfolds the substrate, and proteolytically dismantles it into small peptides, with ubiquitin recycled for reuse. This mechanism finely tunes protein levels and removes damaged or misfolded proteins, helping maintain overall protein homeostasis and proper cellular regulation. It doesn’t synthesize new proteins, which is done by ribosomes; it doesn’t store proteins in lysosomes (that’s lysosomal/autophagic degradation); and it doesn’t export proteins out of the cell (that’s the secretory pathway).

Protein turnover and quality control are tightly governed by the ubiquitin-proteasome system. It marks target proteins with ubiquitin chains, signaling that they should be degraded by the proteasome. The 26S proteasome recognizes these ubiquitin tags, unfolds the substrate, and proteolytically dismantles it into small peptides, with ubiquitin recycled for reuse. This mechanism finely tunes protein levels and removes damaged or misfolded proteins, helping maintain overall protein homeostasis and proper cellular regulation. It doesn’t synthesize new proteins, which is done by ribosomes; it doesn’t store proteins in lysosomes (that’s lysosomal/autophagic degradation); and it doesn’t export proteins out of the cell (that’s the secretory pathway).

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