µ-conotoxin GIIIB, Selective blocker of Nav1.4 channels µ-conotoxin GIIIB is a 22-mer peptide originally isolated from the venom of the piscivorous marine snail Conus geographus. µ-conotoxin GIIIB adopts a compact structure consisting of a distorted 310-helix and a small ß-hairpin. µ-conotoxin GIIIB is stabilized by three disulphide bridges and is highly enriched in lysine and arginine residues, forming potential sites of interaction with Na channels. An unusual feature is the presence of three hydroxyproline residues. µ-conotoxin GIIIB is a useful probe to discriminate between neuronal and muscle sodium channels as it exhibits at least a 1000-fold specificity for muscle versus nerve sodium channels. µ-Conotoxin GIIIB selectively blocks Nav1.4 (µ1) voltage-dependent sodium channels, which are predominantly expressed in muscle, with an affinity close to 20 nM. µ-Conotoxin GIIIB appears to physically occlude the channel pore by binding on site I of the Na+ channel. µ-conotoxin GIIIB technical information AA sequence: Arg-Asp-Cys3-Cys4-Thr-Hyp-Hyp-Arg-Lys-Cys10-Lys-Asp-Arg-Arg-Cys15-Lys-Hyp-Met-Lys-Cys20-Cys21-Ala-NH2 Disulfide bonds: Cys3-Cys15, Cys4-Cys20 and Cys10-Cys21 Length (aa): 22 Formula: C101H175N39O30S7 Molecular Weight: 2640.26 Da Appearance: White lyophilized solid Solubility: water and saline buffer CAS number: Source: Synthetic Purity rate: > 97 % See also conotoxin PIIIA and conotoxin CnIIIC http://www.smartox-biotech.com/en/sodium-channel/311-conotoxin-giiib-nav14-blocker

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