A small protein that becomes covalently linked to a protein targeted for degradation. ultraplankton plankton that are smaller than nannoplankton; they are difficult to separate from water unarmoured - Dinokont-type cells that do not have an identifiable plate series and do not have apical pore complexes.

Ubiquitin is a highly conserved, 76-residue protein that is covalently attached to other proteins. Defined as key term in Biochemistry 1.4.2 Overview of the ubiquitin-proteasome system Molecular Biology 2.8.31 Ubiquitination targets proteins for degradation

A ubiquitous protein that, when attached to a second protein, acts as a tag directing that protein for degradation by the proteosome.

A small protein, present in all eukaryotic cells, which plays an important role in tagging proteins destined for proteolytic cleavage (because they are damaged or no longer needed).