120 550 


Selective blocker of Nav1.4 channels

µ-conotoxin GIIIB is a 22 amino acid conopeptide 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 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.

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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 %

Molecular Basis of Isoform-specific μ-Conotoxin Block of Cardiac, Skeletal Muscle, and Brain Na+ Channels

Conus geographus toxins that discriminate between neuronal and muscle sodium channels

Novel Structural Determinants of m-Conotoxin (GIIIB) Block in Rat Skeletal Muscle (m1) Na+ Channels

Hyperpolarized shifts in the voltage dependence of fast inactivation of Nav1.4 and Nav1.5 in a rat model of critical illness myopathy


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