muconotoxins

Muconotoxins, or μ-conotoxins, are a family of peptide toxins produced by cone snails of the genus Conus. They are components of the venom used for prey capture and defense and represent one of several peptide families that contribute to cone snail pharmacology. Structurally, μ-conotoxins are small, cysteine-rich peptides, typically containing 16 to 26 amino acids and stabilized by two to three disulfide bonds that form a compact, resistant scaffold.

Pharmacology and mechanism: The primary action of μ-conotoxins is to block voltage-gated sodium channels (NaV). They bind to extracellular regions of NaV channels and can occlude the pore, preventing sodium influx and inhibiting action potential generation. This leads to paralysis in prey. The activity spectrum includes multiple NaV isoforms, with varying degrees of selectivity for skeletal muscle NaV1.4 and several neuronal isoforms, depending on the peptide sequence. Some μ-conotoxins show subtype preference, which makes them valuable pharmacological tools for studying NaV channel function.

Discovery and nomenclature: μ-Conotoxins were identified as a distinct class of cone snail toxins in the late 20th century. They are designated with the prefix μ-CTX and named according to the producing species and peptide variant. Research has established structure–activity relationships that indicate how the disulfide framework and specific residues influence channel binding and selectivity.

Applications and significance: As selective NaV blockers, μ-conotoxins are used to investigate the physiology and pharmacology of sodium channels and have been explored as templates for the development of targeted ion channel modulators and potential analgesics. Their presence in cone snail venom underscores the chemical diversity of Conus peptides and their value to toxinology and drug discovery.