Which protein modification targets proteins to the proteasome for destruction?

Ubiquitination is a crucial post-translational modification that plays a significant role in targeting proteins for degradation by the proteasome. The process involves the attachment of ubiquitin, a small protein, to lysine residues on the target protein. This modification acts as a signal for the cell's proteasome machinery, which recognizes the ubiquitin tag and subsequently degrades the tagged protein into small peptides.

The importance of ubiquitination lies in its ability to regulate various cellular processes, including the cell cycle, DNA repair, and responses to stress, by controlling the concentration of specific proteins within the cell. When proteins are no longer needed or are damaged, ubiquitination ensures that they are efficiently removed, thus maintaining cellular homeostasis.

In contrast, the other modifications listed do not have the same role in targeting proteins for proteasomal degradation. For example, SUMOylation is involved in regulating protein localization, stability, and activity, but it does not signal for destruction. Acetylation typically affects protein function and interaction without marking them for degradation, and serine phosphorylation is associated with signaling pathways and the activation or inhibition of proteins but does not lead to proteasomal targeting. Thus, ubiquitination is unique in its specific role in tagging proteins