ubiquitination §

Used in UPS to tag proteins for degradation.

First, a lysine residue on the targeted protein is chemically linked to the glycine at the carboxy-terminus of one ubiquitin. Ubiquitin chains are then formed by the lysine at residue K48 of the first ubiquitin to the carboxy-terminal glycine of a second ubiquitin and so on until at least 4 ubiquitin molecules are bound.