How are substrates recognized by the ubiquitin-mediated proteolytic system?
A necessary step in the degradation of proteins by the ubiquitin system is recognition by the ubiquitin-protein ligases(s). Various structural features of the proteolytic substrate render it susceptible to conjugation with ubiquitin. The N-terminal residue plays a major role in this process, with distinct sites on the ligase(s) recognizing specific types of N-termini. Post-translational modification of some of these residues is required prior to their recognition. A free N terminus is not the only marker; proteins with either free or blocked N termini can be recognized via structural domains that are downstream and distinct from this residue.
Ciechanover
A
A
Schwartz
A L
AL
D008025:Ligases / Q000378:metabolism*; D011489:Protein Denaturation; D012343:RNA, Transfer / Q000378:metabolism; D013379:Substrate Specificity; D044767:Ubiquitin-Protein Ligases
D012343:RNA, Transfer; D044767:Ubiquitin-Protein Ligases; D008025:Ligases