FIGURE 1

Polyubiquitin modification and protein function. Polyubiquitination is highly specific and often requires priming phosphorylation of the substrate to allow E3 ligase recognition and transfer of ubiquitin. Attachment to different lysines (K48 or K63) gives different structures and results either in recognition by the proteasome and destruction or recognition by protein complexes and signal transduction. Specific K48 or K63 DUBs control the reverse process.