Figure 2. Functional implications of interactions between ubiquitin and UBD-containing protein.

(A)Protein complex assembly enabling protein oligomerization through combinatorial use of ubiquitin binding and ubiquitination. (B) Regulation of activity of the UBD-containing protein (exemplified by membrane binding) through conformational changes caused by ubiquitination. (C) Autoinhibition of the ubiquitin-binding ability of the ubiquitin receptors through self-binding. (D) Ubiquitination of ubiquitin receptors resulting in down-regulation by degradation.