Characterization of NAD: Arginine Mono(ADP-Ribosyl)-Transferases in Turkey Erythrocytes: Determinants of Substrate Specificity

Mono(ADP-ribosylation) is catalyzed by transferases identified in viruses, bacteria, and animal cells [1]. Its function has thus far been clearly defined only for certain bacterial toxins that exert their effects on animal tissues by catalyzing the mono(ADP-ribosylation) of critical cellular proteins [1–5]. One of these toxins, choleragen (cholera toxin), an NAD:arginine mono(ADP-ribosyl)transferase, causes the activation of the hormone-sensitive adenylate cyclase from animal tissues by ADP-ribosylating a guanine nucleotide-binding stimulatory protein termed Gs [5]. In vitro, choleragen also catalyzes the ADP-ribosylation of several proteins not related to the cyclase system as well as low molecular weight guanidino compounds, such as the amino acid arginine [6–8]. Animal tissues contain NAD:arginine (ADP-ribosyl)transferases that catalyze reactions similar to those of choleragen [7, 9–11].