Stimulates proteasome activity, probably by ADP-ribosylation of PI31 (PubMed:23622245). Modulates 26S proteasome assembly (PubMed:23622245). NAD(+) + (ADP-D-ribosyl)n-acceptor = nicotinamide + (ADP-D-ribosyl)n+1-acceptor + H(+). L-aspartyl-[protein] + NAD(+) = 4-O-(ADP-D-ribosyl)-L-aspartyl-[protein] + nicotinamide L-glutamyl-[protein] + NAD(+) = 5-O-(ADP-D-ribosyl)-L-glutamyl-[protein] + nicotinamide Interacts (via ANK repeats) with PI31. Belongs to the ARTD/PARP family.