The 26S proteasome degrades polyubiquitinated proteins in the cytoplasm and nucleus. It is formed from a cylindrical catalytic core 20S proteasome capped at each end by a regulatory 19S particle. The 19S regulatory particle recognizes, unfolds, and translocates ubiquitinated proteins into the catalytic core particle in an ATP-dependent manner. Within the regulatory particle base, six paralogous AAA-ATPases, termed Rpt1-Rpt6, associate in three pairs (Rpt1-Rpt2, Rpt3-Rpt6, Rpt4-Rpt5), which arrange into a ring to form a trimer of dimers. (Adapted from
FBrf0215459 and
PMID:28583440.)
