title: Amino acid sequence of toxin F, a snake venom toxin that blocks neuronal nicotinic receptors.
abstract: The amino acid sequence was determined for toxin F, a component of Bungarus multicinctus venom that blocks nicotinic transmission in the chick ciliary ganglion and the rat superior cervical ganglion. Toxin F was purified by a procedure that includes preparative isoelectric focusing and ion exchange chromatography. Seventy nanomolar toxin F blocks nicotinic transmission in the chick ciliary ganglion; however, the toxin only weakly blocks the binding of 125I-alpha-bungarotoxin to membranes derived from Torpedo californica electroplax (IC50 = 1 microM). These data raise the possibility that toxin F may preferentially recognize neuronal nicotinic receptors. Toxin F focused identically on an isoelectric focusing gel with samples of two similar toxins, bungarotoxin 3.1 and kappa-bungarotoxin. The sequence of toxin F is identical with that recently reported for kappa-bungarotoxin. When the N-terminal portion of bungarotoxin 3.1 was sequenced, it was found to be identical to the other two toxins. These and other data suggest that the 3 toxins are, in fact, the same.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D004557:Electric Organ / Q000378:metabolism; D005726:Ganglia, Parasympathetic / Q000187:drug effects; D007525:Isoelectric Focusing; D009498:Neurotoxins / Q000302:isolation & purification / Q000494:pharmacology; D011978:Receptors, Nicotinic / Q000187:drug effects*; D030162:Reptilian Proteins; D012910:Snake Venoms / Q000302:isolation & purification / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects; D014101:Torpedo
chemical_list: D009498:Neurotoxins; D011978:Receptors, Nicotinic; D030162:Reptilian Proteins; D012910:Snake Venoms; C041907:snake venom neurotoxin F