Reconstitution of the 26S proteasome reveals functional asymmetries in its AAA+ unfoldase

In the eukaryotic 26S proteasome, a heterohexameric AAA+ complex unfolds substrates prior to degradation. The yeast unfoldase subunits have now been expressed in bacteria and reconstituted into active proteasomes in vitro. Mutations of catalytic and structural motifs in each individual subunits reveal that they play distinct roles in substrate processing, peptidase binding and gate opening.