An Archaeal Homolog of Proteasome Assembly Factor Functions as a Proteasome Activator (original) (raw)
Figure 1
PbaB binds the mature 20S proteasome through its HbYX motif.
(A and B) PbaB binds to the mature 20S proteasomes (A) αβ1 form and (B) αβ1β2 form but PbaA does not. The non-tagged PbaA and/or PbaB were mixed with the mature 20S proteasome [His6-tagged inactive mutants shown as His6-20S(αβ1) and His6-20S(αβ1β2)] immobilized on Ni2+-charged chelating Sepharose beads. After extensive washing, bound proteins were analyzed by CBB staining after SDS-PAGE. (C) PbaB binds to the mature 20S proteasome (αβ1 form) through its HbYX motif. The PbaB mutant lacking the three amino acid residues constituting the HbYX motif (CΔ3) did not interact with the mature 20S proteasome. (D) PbaB does not form a heteromeric complex with PbaA. Pull-down experiments were performed using a lysate from the co-expressing cells. Asterisks indicate impurities.