CHARACTERIZATION OF A RABBIT SERUM RAISED AGAINST A BOTULINUM TOXIN TYPE-A BINDING-PROTEIN FROM PRESYNAPTIC PLASMA-MEMBRANES FROM TORPEDO ELECTRIC ORGAN

Botulinum neurotoxin type A blocks acetylcholine release from the peri pheral nervous system. We have previously described a putative botulin um neurotoxin type A receptor of presynaptic plasma membranes from Tor pedo. The electric organ of Torpedo, which is largely enriched in chol inergic nerve endings, is homologous to the neuromuscular junction, al lowing us to isolate large scale of presynaptic components. In order t o characterize this protein we have raised a polyclonal antibody (a-P1 40) against this receptor. The antiserum a-P140 recognizes a 140,000 m ol. wt band in non-reducing conditions and an 80,000 band in reducing conditions. The immunohistochemistry assay reveals the P140 protein on the ventral face of the electrocytes where the nerve terminals are lo calized. Moreover, a-P140 antiserum recognizes the P140-BoNT/A complex after binding and cross-linking experiments. In addition, we have imm unoprecipitated an in vitro translated product which is closely coinci dent in mol. wt to the 80,000 band of the receptor.