Alpha-latrotoxin
A latrotoxin is a high-molecular mass neurotoxin found in the venom of spiders of the genus ''Latrodectus'' (widow spiders) as well as at least one species of another genus in the same family, ''Steatoda nobilis''. Latrotoxins are the main active components of the venom and are responsible for the symptoms of latrodectism. The following latrotoxins have been described: five insecticidal toxins, termed α, β, γ, δ and ε-latroinsectotoxins, one vertebrate-specific neurotoxin, alpha-latrotoxin, and one toxin affecting crustaceans, α-latrocrustatoxin. α-Latrotoxin The best-studied latrotoxin is alpha-latrotoxin, which acts presynaptically to release neurotransmitters (including acetylcholine) from sensory and motor neurons, as well as on endocrine cells (to release insulin, for example). It is a ~130 kDa protein that exists mainly in its dimerized or tetramerized forms. α-Latrotoxin (α-LTX) can naturally be found in widow spiders of the genus ''Latrodectus''. The most w ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Latrodectus
''Latrodectus'' is a broadly distributed genus of spiders with several species that are commonly known as the true widows. This group is composed of those often loosely called black widow spiders, brown widow spiders, and similar spiders. However, the diversity of species is much greater. A member of the family Theridiidae, this genus contains 34 species, which include several North American "black widows" (southern black widow '' Latrodectus mactans'', western black widow '' Latrodectus hesperus'', and northern black widow '' Latrodectus variolus''). Besides these, North America also has the red widow '' Latrodectus bishopi'' and the brown widow '' Latrodectus geometricus'', which, in addition to North America, has a much wider geographic distribution. Elsewhere, others include the European black widow (''Latrodectus tredecimguttatus''), the Australian redback black widow (''Latrodectus hasseltii'') and the closely related New Zealand katipō (''Latrodectus katipo''), several ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Latrodectism
Latrodectism () is the illness caused by the bite of ''Latrodectus'' spiders (the black widow spider and related species). Pain, muscle rigidity, vomiting, and sweating are the symptoms of latrodectism. There are several spider species all named black widow: southern black widow spider (''L. mactans''), the European black widow (''L. tredecimguttatus''), Western black widow spider (''L. hesperus''), Northern black widow spider (''L. variolus''). Other ''Latrodectus'' that cause latrodectism are the Australian redback spider (''L. hasselti''), the New Zealand katipō spider (''L. katipo'') and the South American ''Latrodectus corallinus'' and '' Latrodectus curacaviensis''. Several other members of the genus ''Latrodectus'' are not commonly associated with latrodectism including the cosmopolitan brown widow (''L. geometricus''). Signs and symptoms Symptoms of a bite depend on the amount of venom injected. A bite of ''Latrodectus'' may not inj ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Molecular Mass
The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quantity relative molecular mass, as defined by IUPAC, is the ratio of the mass of a molecule to the unified atomic mass unit (also known as the dalton) and is unitless. The molecular mass and relative molecular mass are distinct from but related to the molar mass. The molar mass is defined as the mass of a given substance divided by the amount of a substance and is expressed in g/mol. That makes the molar mass an average of many particles or molecules, and the molecular mass the mass of one specific particle or molecule. The molar mass is usually the more appropriate figure when dealing with macroscopic (weigh-able) quantities of a substance. The definition of molecular weight is most authoritatively synonymous with relative molecular mass; ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Cytosol
The cytosol, also known as cytoplasmic matrix or groundplasm, is one of the liquids found inside cells ( intracellular fluid (ICF)). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondrion into many compartments. In the eukaryotic cell, the cytosol is surrounded by the cell membrane and is part of the cytoplasm, which also comprises the mitochondria, plastids, and other organelles (but not their internal fluids and structures); the cell nucleus is separate. The cytosol is thus a liquid matrix around the organelles. In prokaryotes, most of the chemical reactions of metabolism take place in the cytosol, while a few take place in membranes or in the periplasmic space. In eukaryotes, while many metabolic pathways still occur in the cytosol, others take place within organelles. The cytosol is a complex mixture of substances dissolved in water. Although water forms the large majority of the cytosol, its structure and prop ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Angiotensin-converting Enzyme
Angiotensin-converting enzyme (), or ACE, is a central component of the renin–angiotensin system (RAS), which controls blood pressure by regulating the volume of fluids in the body. It converts the hormone angiotensin I to the active vasoconstrictor angiotensin II. Therefore, ACE indirectly increases blood pressure by causing blood vessels to constrict. ACE inhibitors are widely used as pharmaceutical drugs for treatment of cardiovascular diseases. Other lesser known functions of ACE are degradation of bradykinin, substance P and amyloid beta-protein. Nomenclature ACE is also known by the following names: * dipeptidyl carboxypeptidase I * peptidase P * dipeptide hydrolase * peptidyl dipeptidase * angiotensin converting enzyme * kininase II * angiotensin I-converting enzyme * carboxycathepsin * dipeptidyl carboxypeptidase * "hypertensin converting enzyme" peptidyl dipeptidase I * peptidyl-dipeptide hydrolase * peptidyldipeptide hydrolase * endothelial cell peptidyl dipeptidas ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Peptide
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A polypeptide is a longer, continuous, unbranched peptide chain. Hence, peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. A polypeptide that contains more than approximately 50 amino acids is known as a protein. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, or to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Mediterranean Black Widow
''Latrodectus tredecimguttatus'', also known as the Mediterranean black widow, or the European black widow, is a species in the genus ''Latrodectus'' of the widow spiders. It is commonly found throughout the Mediterranean region, ranging from southern Iberia to southwest and central Asia, hence the name. Specimens from central Asia are also known by the binomial name ''Latrodectus lugubris''; that name, however, is now considered improper, though it is still commonly found in the literature. ''Latrodectus tredecimguttatus'' was previously considered a subspecies of ''Latrodectus mactans''. Description ''L. tredecimguttatus'' is black in color, similar to most other widow species, and is identified by the thirteen spots which are found on its dorsal abdomen (the species name is Latin for "with thirteen spots"). These spots are usually red in colour, but may also be yellow or orange. It is otherwise similar to other species in the genus ''Latrodectus''. The Mediterranean widow p ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Signal Transduction
Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway. When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events. At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location. These molecular events are the basic mechanisms controlling cell gro ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Protein Tyrosine Phosphatase Sigma
Protein tyrosine phosphatases (EC 3.1.3.48, systematic name protein-tyrosine-phosphate phosphohydrolase) are a group of enzymes that remove phosphate groups from phosphorylated tyrosine residues on proteins: : proteintyrosine phosphate + H2O = proteintyrosine + phosphate Protein tyrosine (pTyr) phosphorylation is a common post-translational modification that can create novel recognition motifs for protein interactions and cellular localization, affect protein stability, and regulate enzyme activity. As a consequence, maintaining an appropriate level of protein tyrosine phosphorylation is essential for many cellular functions. Tyrosine-specific protein phosphatases (PTPase; ) catalyse the removal of a phosphate group attached to a tyrosine residue, using a cysteinyl-phosphate enzyme intermediate. These enzymes are key regulatory components in signal transduction pathways (such as the MAP kinase pathway) and cell cycle control, and are important in the control of cell growth ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Tetramers
A tetramer () (''tetra-'', "four" + '' -mer'', "parts") is an oligomer formed from four monomers or subunits. The associated property is called ''tetramery''. An example from inorganic chemistry is titanium methoxide with the empirical formula Ti(OCH3)4, which is tetrameric in solid state and has the molecular formula Ti4(OCH3)16. An example from organic chemistry is kobophenol A, a substance that is formed by combining four molecules of resveratrol. In biochemistry, it similarly refers to a biomolecule formed of four units, that are the same ( homotetramer), i.e. as in Concanavalin A or different ( heterotetramer), i.e. as in hemoglobin. Hemoglobin has 4 similar sub-units while immunoglobulins have 2 very different sub-units. The different sub-units may have each their own activity, such as binding biotin in avidin tetramers, or have a common biological property, such as the allosteric binding of oxygen in hemoglobin. See also * Cluster chemistry; atomic and molecular cl ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Latrophilin
Latrophilins are a group of highly conserved G-protein coupled receptors from the adhesion G protein-coupled receptor family. These receptors were originally identified based on their ability to bind to a component of black widow spider venom known as alpha-latrotoxin. This conserved family of membrane proteins has up to three homologues in chordate species, including humans. The precise functions of latrophilins remain unknown. Genetic defects in latrophilin genes have been associated with diseases such as attention-deficit hyperactivity disorder and cancer. Human proteins containing this domain * Latrophilin 1 ( LPHN1) * Latrophilin 2 (LPHN2) * Latrophilin 3 (LPHN3) See also * ELTD1 EGF, latrophilin and seven transmembrane domain-containing protein 1 is a latrophilin-like orphan receptor of the adhesion G protein-coupled receptor family. In humans this protein is encoded by the ''ELTD1'' gene. ELTD1 appears to have a role i ... References {{Acetylcholine metabo ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Neurexin
Neurexins (NRXN) are a family of presynaptic cell adhesion proteins that have roles in connecting neurons at the synapse. They are located mostly on the presynaptic membrane and contain a single transmembrane domain. The extracellular domain interacts with proteins in the synaptic cleft, most notably neuroligin, while the intracellular cytoplasmic portion interacts with proteins associated with exocytosis. Neurexin and neuroligin "shake hands," resulting in the connection between the two neurons and the production of a synapse. Neurexins mediate signaling across the synapse, and influence the properties of neural networks by synapse specificity. Neurexins were discovered as receptors for α-latrotoxin, a vertebrate-specific toxin in black widow spider venom that binds to presynaptic receptors and induces massive neurotransmitter release. In humans, alterations in genes encoding neurexins are implicated in autism and other cognitive diseases, such as Tourette syndrome and ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |