ADP‐ribosylation of specific membrane proteins in pheochromocytoma and primary‐cultured brain cells by botulinum neurotoxins type C and D

Type C1 and D toxins produced by Clostridium botulinum caused ADP-ribosylation of a protein of 24 kDa in membrane preparations of rat clonal pheochromocytoma cells (PC12) and of proteins of 25 and 26 kDa in neuron-rich culture of fetal rat brain cells. The ADP-ribosylation reaction was dependent on the presence of MgCl2, GTP and GTP gamma S. The results obtained suggested that the ADP-ribosylation reaction is responsible for the development of the biological activity of the botulinum neurotoxins and that the target of this reaction may be novel GTP-binding proteins localized on cell membranes.