1K(B)-PMTX is a mutated form of the (B)-PMTX, originaly isolated from the solitary wasp (Batozonellus maculifrons) venom and is a synthetic version of the peptide. Pompilidotoxins (PMTX, (A) and (B)) are small peptides consisting of 13 amino acids.
(B)-PMTX induces a unique pattern of repetitive action potentials previous seen with other neurotoxins and thus facilitates both excitatory and inhibitory synaptic transmission. Recently it was found that this toxin slows the Na+-channel inactivation, without changing the peak current-voltage relationship or the activation time course of the TTX-sensitive Na+ currents in the neuromuscular synapse of the lobster walking leg and in the rat trigeminal ganglion neurons. It is effective at concentrations of 10 nM in cultured rat cortical neurons.
1K(B)-PMTX is mutated at position 1 with Arginine to Lysine transition, which enhances its activity on voltage-gated human Nav1.6 Na+ Channels relative to native (B)-PMTX.