Tagging of target proteins with polyubiquitin chains.

Ubiquitin is an abundant and highly conserved small protein that consists of 76 amino acids.

The reversible covalent linkage of ubiquitin onto the target protein –called ubiquitination - is a multistep pathway whereby 3-4 different classes of enzymes are involved.

Ubiquitin

Ubiquitination

Hierarchical structure of the ubiquitin system

Substrate specificity of the ubiquitination

References

 

Degradation of proteins by the ubiquitin-proteasome-system