Which is required for protein degradation by the proteasome?

Protein degradation by the proteasome requires the tagging of proteins with ubiquitin, a small protein that signals for their destruction. This ubiquitination process marks the proteins for recognition by the proteasome. Once recognized, the proteasome unfolds and translocates the substrate protein into its catalytic core, where it is degraded into smaller peptides. ATP is also required to provide the energy necessary for this process.