176 985 


Blocker of Kv2 channels

Stromatoxin-1 (ScTx-1) has been isolated from the venom of the African tarentula Stromatopelma calceata.Stromatoxin-1 is a 34 amino-acid long peptide that belongs to the structural family of inhibitor cystine knot peptides reticulated by three disulfide bridges. It has an amidated C-terminus and bears strong homology with hanatoxin 1 (83%).Stromatoxin-1 inhibits with high affinities Kv2.1 and Kv2.2, that encode delayed K+ channels (respectively, with IC50 of 12 and 21 nM). The block is voltage-dependent and slowly reversible. Stromatoxin-1 is also a very sensitive inhibitor of Kv4.2, that encodes a transient K+ current (IC50 of 1.2 nM). Here also, the block is voltage-dependent indicating that ScTx-1 acts as a gating modifier rather than a pore blocker. Reversibility is faster on Kv4.2 channels. In contrast,Stromatoxin-1 has no effect on Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv1.5, Kv1.6 or Kv3.4 channels. The toxin has also no effect on voltage-dependent Na+ and Ca2+ channels of cerebellar granule cells. Stromatoxin-1 was found to increase the spontaneous phasic contraction amplitude, muscle force and tone in isolated rat urinary bladder smooth muscle. It also enhances myogenic constriction in pressurized arterial segments.

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AA sequence : Asp-Cys2-Thr-Arg-Met-Phe-Gly-Ala-Cys9-Arg-Arg-Asp-Ser-Asp-Cys15-Cys16-Pro-His-Leu-Gly-Cys21-Lys-Pro-Thr-Ser-Lys-Tyr-Cys28-Ala-Trp-Asp-Gly-Thr-Ile-NH2
Disulfide bonds : Cys2-Cys16, Cys9-Cys21 and Cys15-Cys28
Length (aa) : 34
Formula : C156H237N49O48S7
Molecular Weight :  3791,3 Da
Appearance : white lyophilized solid
Solubility : water or saline buffer
CAS number :
Source : Synthetic
Purity rate : > 98%

Kv2 dysfunction after peripheral axotomy enhances sensory neuron responsiveness to sustained input

Voltage-gated K+ channels sensitive to stromatoxin-1 regulate myogenic and neurogenic contractions of rat urinary bladder smooth muscle

KV2.1 and electrically silent KV channel subunits control excitability and contractility of guinea pig detrusor smooth muscle

Mechanism of estradiol-induced block of voltage-gated K+ currents in rat medial preoptic neurons

Postnatal development of A-type and Kv1- and Kv2-mediated potassium channel currents in neocortical pyramidal neurons

Stromatoxin-sensitive, heteromultimeric Kv2.1/Kv9.3 channels contribute to myogenic control of cerebral arterial diameter

Participation of KCNQ (Kv7) potassium channels in myogenic control of cerebral arterial diameter

Membrane potential-dependent inactivation of voltage-gated ion channels in alpha-cells inhibits glucagon secretion from human islets

Voltage-gated ion channels in human pancreatic beta-cells: electrophysiological characterization and role in insulin secretion

Structural basis of binding and inhibition of novel tarantula toxins in mammalian voltage-dependent potassium channels

Novel Tarantula Toxins for Subtypes of Voltage-Dependent Potassium Channels in the Kv2 and Kv4 Subfamilies

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