Degron

[1][5] Degrons are present in a variety of organisms, from the N-degrons (see N-end Rule) first characterized in yeast[6] to the PEST sequence of mouse ornithine decarboxylase.

[10][11] Ubiquitin-dependent degrons are so named because they are implicated in the polyubiquitination process for targeting a protein to the proteasome.

[15][16] In some cases, the degron itself serves as the site for polyubiquitination as is seen in TAZ and β-catenin proteins.

[9][10][11] Recall that degrons are often referred to as “ubiquitin-dependent” or “ubiquitin-independent” The third step performed is often done after one or both of the previous two steps, because it serves to identify the ubiquitin dependence or lack thereof of a previously identified degron.

[1][7][20] A significant increase in the amount of ubiquitin in A’ as compared to A will suggest that the degron is ubiquitin-dependent.

Shown here in green is a portion of IκBα , an inhibitor of NF-κB and regulator of the immune system. The red region highlights the sixth ankyrin repeat domain, which contains a ubiquitin-independent degron. [ 1 ]
Shown is a diagram representing two degron-identifying procedures outlined in the text. In the first (green) procedure, the unaltered form of the protein remains abundant over time while the mutant form containing a degron candidate decreases rapidly. In the second (red) procedure the unaltered form of a protein containing the degron candidate decreases rapidly over time while the mutant form stripped of its degron remains abundant. A' versus A are used to notate protein forms containing the degron vs not containing the degron.