Target protein for eucaryotic arginine-specific ADP-ribosyltransferase

Among ADP-ribosyltransferases reported in eucaryotes, arginine-specific transferases from turkey erythrocytes, chicken heterophils and rabbit skeletal muscle have been purified and extensively studied. They were reported to modify a number of proteinsin vitro. ADP-ribosylation of Ha-ras-p21 and transducin by the turkey erythrocyte transferase inhibits their GTPase and GTP-binding activities. Chicken heterophil enzyme modifies several substrate proteins for protein kinases and decreases the phosphate-acceptor activity. Rabbit skeletal muscle Ca²⁺-ATPase is inhibited by ADP-ribosylation catalyzed by the muscle transferase. Three transferases all ADP-ribosylate small molecular weight guanidino compounds such as arginine, arginine methylester and agmatine and poly-L-arginine and nuclear histones. However, the observation that muscle transferase did not ADP-ribosylate casein or actin, both of which can be modified by the heterophil transferase under the same conditions indicates that substrate specificity of these two enzymes are different. Substrate-dependent effects were observed with polyions of nucleotides such that polyanions stimulate the ADP-ribosylation of possible target protein, p33 by chicken heterophil transferase but has no effect on the modification of casein by the same enzyme.