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Updated: Oct 16, 2026

Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time
Published on: March 11, 2021
Molecular determinants of binding of a wasp toxin (PMTXs) and its analogs in the Na+ channels proteins
1Institute of Biosciences at Rio Claro, São Paulo State University, Brazil.
Abstract:
The structural specificity of alpha-PMTX, a novel peptide toxin derived from wasp venom has been studied on the neuromuscular synapse in the walking leg of the lobster. alpha-PMTX is known to induce repetitive action potentials in the presynaptic axon due to sodium channel inactivation. We synthesized 29 analogs of alpha-PMTX by substituting one or two amino acids and compared threshold concentrations of these mutant toxins for inducing repetitive action potentials. In 13 amino acid residues of alpha-PMTX, Arg-1, Lys-3 and Lys-12 regulate the toxic activity because substitution of these basic amino acid residues with other amino acid residues greatly changed the potency. Determining the structure-activity relationships of PMTXs will help clarifying the molecular mechanism of sodium channel inactivation.
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