How does Latrotoxin affect synapse?
alpha-Latrotoxin, a potent neurotoxin from black widow spider venom, triggers synaptic vesicle exocytosis from presynaptic nerve terminals. Binding of alpha-latrotoxin to these receptors does not in itself trigger exocytosis but serves to recruit the toxin to the synapse.
What is Latrotoxin made of?
α-Latrotoxin is a presynaptic neurotoxin isolated from the venom of the black widow spider Latrodectus tredecimguttatus. It exerts toxic effects in the vertebrate central nervous system by depolarizing neurons, by increasing [Ca2+]i and by stimulating uncontrolled exocytosis of neurotransmitters from nerve terminals.
How does Latrotoxin affect acetylcholine?
Binding of α-latrotoxin to neuronal receptors results in massive release of acetylcholine (ACh) at the neuromuscular junction, resulting in profound muscle contraction. The symptoms of toxicosis relate to this neuromuscular activity and include muscle spasms, muscle pain, and abdominal rigidity.
Is Latrotoxin an antagonist?
The seven membrane-spanning domains of CIRL, which are homologous to those of the members of the secretin receptor family, suggest that α-latrotoxin may work as an agonist or antagonist of CIRL initiating intracellular signaling via a heterotrimeric G protein in a calcium-independent manner.
How does Latrotoxin the venom of the black widow spider cause muscle spasms and rigidity?
Unique to the widows is latrotoxin. The venom acts on nerves causing the massive release of the neurotransmitters acetylcholine, norepinephrine, and GABA. The release of these neurotransmitters leads to pain, cramps, sweating and fast pulse.
Is brown recluse venom a neurotoxin?
Spiders like the southern black widow, the brown recluse, the brown widow and even the common house spider can inflict medically significant bites to humans. Neurotoxic venom is produced by all five widow spider species in the United States, including the southern black widow and the brown widow.
Where is latrotoxin active?
A latrotoxin is a high-molecular mass neurotoxin found in the venom of spiders of the genus Latrodectus (widow spiders) and also found in the venom of spider species, Steatoda nobilis. Latrotoxins are the main active components of the venom and are responsible for the symptoms of latrodectism.
Is latrotoxin an antagonist?
How does latrotoxin the venom of the black widow spider cause muscle spasms and rigidity?
Is black widow venom an agonist?
Black widow spider venom is an agonist (a chemical substance that mimics or enhances the effects of a neurotransmitter) for ACh. The venom of the black widow spider causes a flood of acetylcholine to be released into the body’s muscle system, causing convulsions.
How does black widow venom affect acetylcholine?
An extract of the venom glands of black widow spiders (BWGE) induces the release of acetylcholine (ACh) from the superior cervical ganglia of rats. The release of ACh follows first-order kinetics, which suggests that the venom either lowers the ganglionic store of ACh, or continually reduces the rate of release.
How does α-latrotoxin stimulate exocytosis?
Regardless of the complex mode of action, α -latrotoxin stimulates exocytosis only after binding to neuronal cell surface receptors. The first receptor to be discovered was neurexin 1 α, a neuronal protein with a single transmembrane domain. However, neurexin 1 α binds to α -latrotoxin only in the presence of Ca 2+.
What is latrophilin and alpha-latrotoxin?
On the other hand, latrophilin is a seven-transmembrane protein and belongs to the family of G-protein-coupled receptors. The multitude of effects of alpha-latrotoxin on exocytosis in different cell systems and the nature of its membrane targets are discussed in this article.
How many domains are there in α-latrotoxin?
Thus, mature α -latrotoxin is composed of two domains (domains II and III). α -Latrotoxin has a complex mode of action: it stimulates neurotransmitter release from neurons in the presence or absence of extracellular Ca 2+, and it also stimulates neurotransmitter release from neuroendocrine cells, but only in the presence of Ca 2+.
What are the novel alpha latrotoxin-binding membrane receptors?
Recently, sophisticated biochemical and molecular techniques have led to the discovery of novel alpha latrotoxin-binding membrane receptors: neurexins and latrophilin/CIRL (calcium-independent receptor for alpha-latrotoxin).