|
Spider Toxin
Spider toxins are a family of proteins produced by spiders which function as neurotoxins. The mechanism of many spider toxins is through blockage of calcium channels. A remotely related group of atracotoxins operate by opening sodium channels. Delta atracotoxin from the venom of the Sydney funnel-web spider produces potentially fatal neurotoxic symptoms in primates by slowing the inactivation of voltage-gated sodium channels. The structure of atracotoxin comprises a core beta region containing a triple-stranded a thumb-like extension protruding from the beta region and a C-terminal helix. The beta region contains a cystine knot motif, a feature seen in other neurotoxic polypeptides and other spider toxins, of the CSTX family. Spider potassium channel inhibitory toxins is another group of spider toxins. A representative of this group is hanatoxin, a 35 amino acid peptide toxin which was isolated from Chilean rose tarantula (''Grammostola rosea'', syn. ''G. spatulata'') venom. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agelenopsis Aperta
''Agelenopsis aperta'', also known as the desert grass spider or funnel-web spider, is a species of spider belonging to the family Agelenidae and the genus ''Agelenopsis''. It is found in dry and arid regions across the southern United States and into northwestern Mexico. Their body is about 13–18 mm long and they have relatively long legs in order to run after their prey. Desert grass spiders can withstand very low temperatures even though they do not Cold hardening, cold harden. It constructs the characteristic funnel-shaped webs in crevices where the funnel will fit, where they wait in the tube for prey which they can run after using their long legs. They often hunt for their prey at night. ''A. aperta'' is known for its territoriality and will fight intruders to protect their space. ''A. aperta'' are mainly monogamous, and the male performs an elaborate courtship ritual that involves swaying his abdomen and releasing pheromones. The male's pheromones induce a cataplec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hanatoxin
Hanatoxin is a toxin found in the venom of the '' Grammostola spatulata'' tarantula. The toxin is mostly known for inhibiting the activation of voltage-gated potassium channels, most specifically Kv4.2 and Kv2.1, by raising its activation threshold. Sources Hanatoxin is a spider toxin from the venom of ''Grammostola spatulata''. Chemistry Hanatoxin is the common name for two 4.1 kDa protein toxins, HaTx1 and HaTx2, which are similar in structure. HaTx is a peptide consisting of the following 35 amino-acids: Glu-Cys-Arg-Tyr-Leu-Phe-Gly-Gly-Cys-Lys-Thr-Thr-***-Asp-Cys-Cys-Lys-His-Leu-Gly-Cys-Lys-Phe-Arg-Asp-Lys-Tyr-Cys-Ala-Trp-Asp-Phe-Thr-Phe-Ser where *** is Ser for HaTx1 and Ala for HaTx2. First discovered in 1995, the difference in amino-acids and structure compared to other toxins known at that time has made hanatoxin the founding member of a family of spider toxins which inhibit voltage-gated potassium channels by modifying the voltage-sensor. Its amino-acid sequenc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Domains
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins. Molecular evolution uses domains as building blocks and these may be recombined in different arrangements to create proteins with different functions. In general, domains vary in length from between about 50 amino acids up to 250 amino acids in length. The shortest domains, such as zinc fingers, are stabilized by metal ions or disulfide bridges. Domains often form functional units, such as the calcium-binding EF hand domain of calmodulin. Because they are independently stable, domains can be "swapped" by genetic engineering between one protein and another to make chimeric proteins. Background The concept of the domain was first proposed in 1973 by Wetlaufer after ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raventoxin
Raventoxins are neurotoxins from the venom of the spider '' Macrothele raveni''. Sources Raventoxins are toxins from the venom of the spider ''Macrothele raveni''. This is a hairy spider, a member of the genus ''Macrothele'', that can be found in the hilly areas of Ningming County, Guangxi Province in China. Chemistry Six different types of raventoxin have been described, named raventoxin-I to VI.Zeng, Xiong-zhi, Liang, Song-ping Purification and Preliminary Toxic Research of Raventoxin-II, a Neurotoxic Peptide from the Venom of the Spider Macrothele raveni . Life Science Research. 2001 september; 5(3): 217-220.Zeng Xiong-zhi, Liang Song-ping. Purification and Preliminary Active Characterization of Raventoxin-V, a Novel Insecticidal Toxin Isolated from the Spider Macrothele Rraveni. Journal of Huaihua University. 2007-04Zhang Peng fei, Chen Ping, Xiao Shun yong, Liang Song ping.Purification, Characterization of Raventoxin-VI from the Venom of the Spider Macrothele raveni Life Sci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huwentoxin
Huwentoxins (HWTX) are a group of neurotoxic peptides found in the venom of the Chinese bird spider '' Haplopelma schmidti''. The species was formerly known as ''Haplopelma huwenum'', ''Ornithoctonus huwena'' and ''Selenocosmia huwena''. While structural similarity can be found among several of these toxins, HWTX as a group possess high functional diversity. Sources Huwentoxins are neurotoxic peptides produced by the Chinese bird spider, ''Haplopelma schmidti''. Overview The venom of ''H. schmidti'' contains a large variety of neurotoxins, which function to paralyze the spider's prey. So far, 14 of the isolated primarily neurotoxic peptide components have been characterized and investigated. In the following, two subfamilies of the HWTX are described: those targeting voltage-gated calcium channels, and those targeting voltage-gated sodium channels. Toxins targeting voltage-gated calcium channels (VGCC) Huwentoxin-I HWTX-I is the most abundant toxic component in the venom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage-gated Potassium Channel
Voltage-gated potassium channels (VGKCs) are transmembrane channels specific for potassium and sensitive to voltage changes in the cell's membrane potential. During action potentials, they play a crucial role in returning the depolarized cell to a resting state. Classification Alpha subunits Alpha subunits form the actual conductance pore. Based on sequence homology of the hydrophobic transmembrane cores, the alpha subunits of voltage-gated potassium channels are grouped into 12 classes. These are labeled Kvα1-12. The following is a list of the 40 known human voltage-gated potassium channel alpha subunits grouped first according to function and then subgrouped according to the Kv sequence homology classification scheme: Delayed rectifier slowly inactivating or non-inactivating *Kvα1.x - Shaker-related: Kv1.1 (KCNA1), Kv1.2 (KCNA2), Kv1.3 (KCNA3), Kv1.5 (KCNA5), Kv1.6 (KCNA6), Kv1.7 ( KCNA7), Kv1.8 (KCNA10) *Kvα2.x - Shab-related: Kv2.1 (KCNB1), Kv2.2 (KCNB2) *Kvα3.x - ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synonym (taxonomy)
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently. * In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linnaeus was the first to give a scientific name (under the currently used system of scientific nomenclature) to the Norway spruce, which he called ''Pinus abies''. This name is no longer in use, so it is now a synonym of the current scientific name, ''Picea abies''. * In zoology, moving a species from one genus to another results in a different binomen, but the name is considered an alternative combination rather than a synonym. The concept of synonymy in zoology is reserved for two names at the same rank that refers to a taxon at that rank - for example, the name ''Papilio prorsa'' Linnaeus, 1758 is a junior synonym of ''Papilio levana'' Linnaeus, 1758, being names for different seasonal forms of the species now referred to as ''Araschnia le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chilean Rose Tarantula
The Chilean rose tarantula (''Grammostola rosea''), also known as the rose hair tarantula, the Chilean fire tarantula, or the Chilean red-haired tarantula (depending on the color morph), is probably the most common species of tarantula available in American and European pet stores today, due to the large number of wild-caught specimens exported cheaply from their native Chile into the pet trade. The species is also known from Bolivia and Argentina.Muller-Esnault, Susan, DVM. "Rose Hair Tarantulas or Chilean Rose Hair" (2008). http://www.critterology.com/rose_hair_tarantulas_or_chilean_rose_hair-192.html ''G. rosea'' is a common pet of tarantula hobbyists. Females have been known to live as long as 20 years, but due to the limited time they have been available on the market (and hence for extensive study), they may live considerably longer than 20 years. Considerable confusion exists between this species and ''Grammostola porteri'', with some arguing that many of the "''G.&nbs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inhibitor Cystine Knot
An inhibitor cystine knot (aka ICK or Knottin) is a protein structural motif containing three disulfide bridges. Knottins are one of three folds in the cystine knot motif; the other closely related knots are the Growth Factor Cystine Knot (GFCK) and the Cyclic Cystine Knot (CCK; cyclotide). Types include a) cyclic mobius, b) cyclic bracelet, c) acyclic inhibitor knottins. Cystine knot motifs are found frequently in nature in a plethora of plants, animals, and fungi and serve diverse functions from appetite suppression to anti-fungal activity. Along with the sections of polypeptide between them, two disulfides form a loop through which the third disulfide bond (linking the 3rd and 6th cysteine in the sequence) passes, forming a knot. The motif is common in invertebrate toxins such as those from arachnids and molluscs. The motif is also found in some inhibitor proteins found in plants, but the plant and animal motifs are thought to be a product of convergent evolution. The ICK moti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Family
A protein family is a group of evolutionarily related proteins. In many cases, a protein family has a corresponding gene family, in which each gene encodes a corresponding protein with a 1:1 relationship. The term "protein family" should not be confused with Family (biology), family as it is used in taxonomy. Proteins in a family descend from a common ancestor and typically have similar protein structure, three-dimensional structures, functions, and significant Sequence homology, sequence similarity. The most important of these is sequence similarity (usually amino-acid sequence), since it is the strictest indicator of homology and therefore the clearest indicator of common ancestry. A fairly well developed framework exists for evaluating the significance of similarity between a group of sequences using sequence alignment methods. Proteins that do not share a common ancestor are very unlikely to show statistically significant sequence similarity, making sequence alignment a powerf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltage-gated Sodium Channels
Sodium channels are integral membrane proteins that form ion channels, conducting sodium ions (Na+) through a cell's membrane. They belong to the superfamily of cation channels and can be classified according to the trigger that opens the channel for such ions, i.e. either a voltage-change ("voltage-gated", "voltage-sensitive", or "voltage-dependent" sodium channel; also called "VGSCs" or "Nav channel") or a binding of a substance (a ligand) to the channel (ligand-gated sodium channels). In excitable cells such as neurons, myocytes, and certain types of glia, sodium channels are responsible for the rising phase of action potentials. These channels go through three different states called resting, active and inactive states. Even though the resting and inactive states would not allow the ions to flow through the channels the difference exists with respect to their structural conformation. Selectivity Sodium channels are highly selective for the transport of ions across cell membr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sydney Funnel-web Spider
The Sydney funnel-web spider (''Atrax robustus'') is a species of venomous Mygalomorphae, mygalomorph spider native to eastern Australia, usually found within a radius of Sydney. It is a member of a group of spiders known as Australian funnel-web spiders. Its bite is capable of causing serious illness or death in humans if left untreated. The Sydney funnel-web has a body length ranging from . Both sexes are glossy and darkly coloured, ranging from blue-black, to black, to shades of brown or dark-plum coloured. Taxonomy Octavius Pickard-Cambridge was the first to describe the Sydney funnel-web spider, from a female specimen housed in the British Museum in 1877. Establishing the genus ''Atrax'', he named it ''Atrax robustus''. The species name is derived from the Latin ''robustus'', "strong/sturdy/mature". Some years later, William Joseph Rainbow described a male Sydney funnel-web as a new species—''Euctimena tibialis''—from a spider he found under a log in Turramurra, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
