Ubiquitin tagging allows the 19S subunit of the 26S proteasome to recognize the potential protein substrate.

Ubiquitin is found in almost all tissues within the body. It is a small regulatory protein which exists in all eukaryotic cells and was discovered in 1975.

Protein degradation would decrease due to ubiquitin's role in delivering to-be-broken-down proteins to the proteasomes.

ubiquitin enzymes

E. Elizabeth Patton has written:

'E3 ubiquitin protein ligase complexes that regulate G1-phase in budding yeast'