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-cysteinyl-[protein] + NAD(+) = H(+) + nicotinamide + S-(ADP-D-ribosyl)-L-cysteinyl-[protein] Auto-mono-ADP-ribosylated. Belongs to the ARTD/PARP family.