ubiquitin

https://doi.org/10.1351/goldbook.13767
Highly conserved 76 amino acid peptide abundant in eukaryotic cells. Its covalent attachment to a protein by a ubiquitin ligase complex targets that protein for destruction by the proteasome.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1257 [Terms] [Paper]