Figure 4.

A, Ubiquitination is a reversible process. DUBs deconjugate ubiquitin-modified proteins and rescue the substrate from proteasomal degradation. B, The balance between GPCR ubiquitination and deubiquitination regulates their surface expression and cellular responsiveness. Greater receptor ubiquitination results in fewer cell surface receptors by virtue of degradation and down-regulation. Conversely, with more DUBs, the final number of receptors that are ubiquitinated is diminished, with less attendant degradation, consequently more receptor recycling, and greater numbers of membrane-delimited GPCRs.