Mono-ADP-ribosyltransferase that mediates mono-ADP-ribosylation of target proteins. 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 Component of the vault ribonucleoprotein particle, at least composed of MVP, PARP4 and one or more vault RNAs (vRNAs). Interacts with TEP1. Localizes in the cytoplasm at steady state, but shuttles between nucleus and cytoplasm in a XPO1-dependent manner. No visible phenotype (PubMed:15169895). Mice are viable and fertile for up to five generations, with no apparent changes in telomerase activity or telomere length (PubMed:15169895). Belongs to the ARTD/PARP family. Extended N-terminus.