Ubiquitin – as the name suggests – is a small ubiquitous protein that is found in all eukaryotic organisms from yeast to humans.  Although it is one of the smallest proteins in the cell it has one of the largest roles in cellular processes.  Nature attaches ubiquitin to lysine residues on other proteins, often growing ubiquitin chains via subsequent attachment of more ubiquitin to the lysines found in ubiquitin itself.

These chains act as “tags”, directing the modified protein to the proteasome for degradation or acting to recruit other proteins for propagation of intracellular signals. Degraders developed by C4T utilize this cellular machinery to target harmful proteins for ubiquitination.  Ubiquitination then directs the target protein for degradation via the proteasome.


The proteasome is the cell’s recycling plant.  Proteins delivered to the proteasome are threaded into the inner core particle where they are disassembled into small peptides, then ultimately degraded to amino acids, which are re-used by the cell to create new proteins. The attachment of ubiquitin chains to the protein is a critical step in delivering a protein to the proteasome for recycling.

Once the ubiquitin tagged protein is brought to the proteasome, it interacts with the regulatory particle composed of the base and the lid. Proteins in the lid remove the ubiquitin tag, allowing ubiquitin to be recycled and not degraded, and then other proteins in the regulatory particle begin to unravel and thread the protein into the core particle for digestion. C4T’s degrader technology triggers the tagging of a disease-causing proteins with a poly-ubiquitin chain (the proteasome delivery label), which enables the cell’s natural processes take over and eliminate the targeted protein.

Learn more about C4T’s approach to creating degraders

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