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CNQX or cyanquixaline (6-cyano-7-nitroquinoxaline-2,3-dione) is a competitive AMPA/kainate receptor antagonist. Its chemical formula is C9H4N4O4. CNQX is often used in the retina to block the responses of OFF-bipolar cells for electrophysiology recordings.
A conotoxin is one of a group of neurotoxic peptides isolated from the venom of the marine cone snail, genus Conus.
The Mexican beaded lizard is a species of lizard in the family Helodermatidae, one of the two species of venomous beaded lizards found principally in Mexico and southern Guatemala. It and the other members of the same genus, including the Gila monster, are the only lizards known to have evolved an overt venom delivery system. The Mexican beaded lizard is larger than the Gila monster, with duller coloration, black with yellowish bands. As it is a specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. This venom has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing.
Ophanin is a toxin found in the venom of the King Cobra, which lives throughout South East Asia. This toxin belongs to the cysteine-rich secretory protein (CRISP) family. Ophanin weakly blocks the contraction of smooth muscles elicited by high potassium-induced depolarization, suggesting that it inhibits voltage-dependent calcium channels.
Calcicludine (CaC) is a protein toxin from the venom of the green mamba that inhibits high-voltage-activated calcium channels, especially L-type calcium channels.
Taicatoxin (TCX) is a snake toxin that blocks voltage-dependent L-type calcium channels and small conductance Ca2+-activated K+ channels. The name taicatoxin (TAIpan + CAlcium + TOXIN) is derived from its natural source, the taipan snake, the site of its action, calcium channels, and from its function as a toxin. Taicatoxin was isolated from the venom of Australian taipan snake, Oxyuranus scutellatus scutellatus. TCX is a secreted protein, produced in the venom gland of the snake.
Margatoxin (MgTX) is a peptide that selectively inhibits Kv1.3 voltage-dependent potassium channels. It is found in the venom of Centruroides margaritatus, also known as the Central American Bark Scorpion. Margatoxin was first discovered in 1993. It was purified from scorpion venom and its amino acid sequence was determined.
The P-type calcium channel is a type of voltage-dependent calcium channel. Similar to many other high-voltage-gated calcium channels, the α1 subunit determines most of the channel's properties. The 'P' signifies cerebellar Purkinje cells, referring to the channel's initial site of discovery. P-type calcium channels play a similar role to the N-type calcium channel in neurotransmitter release at the presynaptic terminal and in neuronal integration in many neuronal types.
Stromatoxin is a spider toxin that blocks certain delayed-rectifier and A-type voltage-gated potassium channels.
Philanthotoxins are components of the venom of the Egyptian solitary wasp Philanthus triangulum, commonly known as the European beewolf. Philanthotoxins are polyamine toxins, a group of toxins isolated from the venom of wasps and spiders which immediately but reversibly paralyze their prey. δ-philanthotoxin, also known as PhTX-433, is the most active philanthotoxin that can be refined from the venom. PhTX-433 functions by non-selectively blocking excitatory neurotransmitter ion channels, including nicotinic acetylcholine receptors (nAChRs) and ionotropic glutamate receptors (iGluRs). Synthetic analogues, including PhTX-343 and PhTX-12, have been developed to improve selectivity. While the IC50 values of philanthotoxins varies between analogues and receptor subunit composition, the IC50 value of PhTX-433 at the iGluR AMPA receptor naturally expressed in locust leg muscle is 18 μM and the IC50 value at rat nAChRs is 1 μM.
Tertiapin is a 21-amino acid peptide isolated from venom of the European honey bee. It blocks two different types of potassium channels, inward rectifier potassium channels (Kir) and calcium activated large conductance potassium channels (BK).
Discrepin (α-KTx15.6) is a peptide from the venom of the Venezuelan scorpion Tityus discrepans. It acts as a neurotoxin by irreversibly blocking A-type voltage-dependent K+-channels.
Ablomin is a toxin present in the venom of the Japanese Mamushi snake, which blocks L-type voltage-gated calcium channels.
BeKm-1 is a toxin from the Central Asian scorpion Buthus eupeus. BeKm-1 acts by selectively inhibiting the human Ether-à-go-go Related Gene (hERG) channels, which are voltage gated potassium ion channels.
Jingzhaotoxin proteins are part of a venom secreted by Chilobrachys jingzhao, the Chinese tarantula. and act as neurotoxins. There are several subtypes of jingzhaotoxin, which differ in terms of channel selectivity and modification characteristics. All subspecies act as gating modifiers of sodium channels and/or, to a lesser extent, potassium channels.
Guangxitoxin, also known as GxTX, is a peptide toxin found in the venom of the tarantula Plesiophrictus guangxiensis. It primarily inhibits outward voltage-gated Kv2.1 potassium channel currents, which are prominently expressed in pancreatic β-cells, thus increasing insulin secretion.
Hadrucalcin is a peptide toxin from the venom of the scorpion Hadrurus gertschi. Hadrucalcin modifies the Ryanodine receptor channels RyR1 and RyR2, found in the sarcoplasmic reticulum, to a long-lasting subconductance state, thus inducing the release of calcium from the sarcoplasmic reticulum.
Vejocalcin (VjCa, also called Vejocalcine) is a toxin from the venom of the Mexican scorpion Vaejovis mexicanus. Vejocalcin is a member of the calcin family of toxins. It acts as a cell-penetrating peptide (CPP); it binds with high affinity and specificity to skeletal ryanodine receptor 1 (RYR1) of the sarcoplasmic reticulum, thereby triggering calcium release from intracellular Ca2+ stores.
Intrepicalcin (ViCaTx1) is a short peptide toxin found in the venom of scorpion Vaejovis intrepidus. It is one of a group of short, basic peptides called calcins, which bind to ryanodine receptors (RyRs) and thereby trigger calcium release from the sarcoplasmic reticulum.
AsKC11 is a toxin found in the venom of the sea anemone, Anemonia sulcata. This toxin is part of the Kunitz peptide family and has been shown to be an activator of G protein-coupled inwardly-rectifying potassium (GIRK) channels 1/2, involved in the regulation of cellular excitability.
References
- 1 2 3 4 5 J. Mochca-Morales, B.M. Martin, L.D. Possani, 1990, Isolation and characterization of helothermine, a novel toxin from Heloderma horridum horridum (Mexican beaded lizard) venom, Toxicon, 28 (3), 299-309
- 1 2 M.E. Adams and G. Swanson, 1994, Neurotoxins, Trends in Neurosciences, 17:1s-28s
- 1 2 3 4 J. Morrissette et al, 1995, Primary structure and properties of Helothermine, a peptide toxin that blocks ryanodine receptors, Biophys. J, 68(6): 2280-8
- 1 2 3 M. Nobile et al, 1996, Helothermine, a lizard venom toxin, inhibits calcium current in cerebellar granules, Exp Brain Res, 110:15-20
- 1 2 3 4 M.Nobile et al, 1994, the toxin HLTx affects potassium currents in newborn rat cerebellar granule cells, J. Membrane Biology, 139: 49-55