Production of monoclonal antibodies that inhibit ADP‐ribosylation of small GTP‐binding proteins catalyzed by Clostridium botulinum ADP‐ribosyltransferase C3

Four monoclonal antibodies that inhibited ADP‐ribosylation of 23 kDa protein(s) of ascidian eggs catalyzed by Clostridium botulinum ADP‐ribosyltransferase C3 were produced. They also inhibited C3‐catalyzed ADP‐ribosylation of the 24 kDa protein of rat liver cytosol. By the immunoprecipitation technique, it was found that they recognized small GTP‐binding proteins of ascidian eggs and mammalian brains, but did not interact with the rat brain activator of the ADP‐ribosyltransferase reaction. The antibody can also immunoprecipitate recombinant Rho A irrespective as to whether the Rho A is the GDP‐bound form or the GTPrS‐bound form. Thus the antibodies are novel and useful tools in analyzing the physiological roles of the Rho family of GTP‐binding proteins.