What effect does Latrotoxin have on muscle fibers?
The toxin acts as a cation pore in the presynaptic neuron allowing influx of calcium which causes depolarization and release of neurotransmitters (primarily acetylcholine). This results in stimulation of skeletal and cardiac muscle fibers, pain, and autonomic hyperactivity.
How does alpha Latrotoxin work?
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.
Why do black widows have such powerful venom?
The researchers also discovered that black widow spider venom contains a cocktail of other toxins that boosts the effectiveness of alpha-latrotoxin. Understanding spider venom could lead to better treatments for bites. Some scientists also believe that the venom holds untapped medical benefits.
What is black widow spider venom made of?
To date, black widow spider venom has been found to contain seven proteins with neurotoxic activity. There are five insectotoxins: α, β, γ, δ, and ε-LIT, with respective molecular masses of 120, 140, 120, 110 and 110 kDa, one latrocrustatoxin, α-LCT (120 kDa), and one vertebrate toxin, α-LTX (130 kDa).
What does Black widow venom do to action potentials?
The venom-induced depolarization of the stretch receptor was caused by an increase in membrane conductance to Na+ and Ca2+. Black widow spider venom also caused an increase in the frequency of miniature inhibitory postsynaptic potentials recorded in the stretch receptor.
How do toxins interfere with neuromuscular transmission?
The toxin inhibits the release of synaptic vesicles from motor nerve terminals and from some cholinergic autonomic terminals. Its onset of action is rather slow and involves a molecular rearrangement, not necessarily endocytosis, that abolishes immunobinding.
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.
What is alpha-latrotoxin used for?
Latrotoxins have been used to study the molecular mechanisms of neurotransmitter exocytosis in vertebrates, insects, and crustaceans. α-Latrotoxin is by far the most studied toxin since it is the only one that stimulates neurosecretion from neurons and neuroendocrine cells of vertebrates.
How does latrotoxin affect neuromuscular junction?
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.
How does α-latrotoxin bind to the membrane?
α-Latrotoxin, a black widow spider neurotoxin, can bind to high affinity receptors on the presynaptic plasma membrane and stimulate massive neurotransmitter release in the absence of Ca2+.
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).
What does latrotoxin do to sodium?
At low, subnanomolar concentrations, α -latrotoxin induces individual, low-conductance channels permeable to sodium, calcium, magnesium, and other cations. At higher concentrations (in the low nanomolar range), the toxin also forms pores permeable to low-molecular-weight substances.
What is the mechanism of action of alpha-latrotoxin?
Mechanisms of alpha-latrotoxin action. Neurexins are single transmembrane proteins which bind to alpha-latrotoxin in a calcium-dependent manner and also interact with the synaptic vesicle protein, synaptotagmin. On the other hand, latrophilin is a seven-transmembrane protein and belongs to the family of G-protein-coupled receptors.
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