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Mastoparan
Mastoparan is a peptide toxin from wasp venom. It has the chemical structure Ile-Asn-Leu-Lys-Ala-Leu-Ala-Ala-Leu-Ala-Lys-Lys-Ile-Leu-NH2. The net effect of mastoparan's mode of action depends on cell type, but seemingly always involves exocytosis. In mast cells, this takes the form of histamine secretion, while in platelets and chromaffin cells release serotonin and catecholamines are found, respectively. Mastoparan activity in the anterior pituitary gland leads to prolactin release. In the case of histamine secretion, the effect of mastoparan takes place via its interference with G protein activity. By stimulating the GTPase activity of certain subunits, mastoparan shortens the lifespan of active G protein. At the same time, it promotes dissociation of any bound GDP from the protein, enhancing GTP binding. In effect, the GTP turnover of G proteins is greatly increased by mastoparan. These properties of the toxin follow from the fact that it structurally resembles activated G pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vespa Simillima
''Vespa simillima'', the yellow hornet, including the color form known as the , is a common hornet Hornets (insects in the genus ''Vespa'') are the largest of the eusocial wasps, and are similar in appearance to their close relatives yellowjackets. Some species can reach up to in length. They are distinguished from other vespine wasps by t ... species in the Eastern Hemisphere. The typical mainland color form (Japanese language, Japanese:ケブカスズメバチ, Korean language, Korean: 털보말벌, "hairy wasp") is darker and hairier than the yellow form; it lives in Hokkaido, the Korean Peninsula, Eastern Siberia and China, but is less common in Japan, where the yellow color form predominates. It should not be confused with the Asian giant hornet (''Vespa mandarinia''), which has a color form sometimes referred to as the "Japanese giant hornet". While there is a history of recognizing subspecies within many hornets, the most recent taxonomic revision treats all subspeci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GTPase
GTPases are a large family of hydrolase enzymes that bind to the nucleotide guanosine triphosphate (GTP) and hydrolyze it to guanosine diphosphate (GDP). The GTP binding and hydrolysis takes place in the highly conserved P-loop "G domain", a protein domain common to many GTPases. Functions GTPases function as molecular switches or timers in many fundamental cellular processes. Examples of these roles include: * Signal transduction in response to activation of cell surface receptors, including transmembrane receptors such as those mediating taste, smell and vision. * Protein biosynthesis (a.k.a. translation) at the ribosome. * Regulation of cell differentiation, proliferation, division and movement. * Translocation of proteins through membranes. * Transport of vesicles within the cell, and vesicle-mediated secretion and uptake, through GTPase control of vesicle coat assembly. GTPases are active when bound to GTP and inactive when bound to GDP. In the generalized recepto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insect Toxins
Insect toxins are various protein toxins produced by insect species. Assassin bugs, sometimes known as kissing bugs, are one of the largest and morphologically diverse families of true bugs feeding on crickets, caterpillars and other insects. Some assassin bug species are bloodsucking parasites of mammals, even feed on humans. They can be commonly found throughout most of the world and their size varies from a few millimeters to as much as 3 or 4 centimeters. The toxic saliva of the predatory assassin bugs contains a complex mixture of small and large peptides for diverse uses such as immobilizing and pre-digesting their prey, as well as defense against competitors and predators. Assassin bug toxins are small peptides with disulfide connectivity that target ion channels. They are relatively homologous to the calcium channel blockers omega-conotoxins from marine cone snails and belong to the four-loop cysteine scaffold structural class. One of these small proteins, Ptu1 Ptu1 is a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrostatic Interactions
Electrostatics is a branch of physics that studies electric charges at rest (static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber, (), was thus the source of the word 'electricity'. Electrostatic phenomena arise from the forces that electric charges exert on each other. Such forces are described by Coulomb's law. Even though electrostatically induced forces seem to be rather weak, some electrostatic forces are relatively large. The force between an electron and a proton, which together make up a hydrogen atom, is about 36 orders of magnitude stronger than the gravitational force acting between them. There are many examples of electrostatic phenomena, from those as simple as the attraction of plastic wrap to one's hand after it is removed from a package, to the apparently spontaneous explosion of grain silos, the damage of electronic components during manufacturin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melittin
Melittin is the main component (40–60% of the dry weight) and the major pain producing substance of honeybee (''Apis mellifera'') venom. Melittin is a basic peptide consisting of 26 amino acids. Function The principal function of melittin as a component of bee venom is to cause pain and destruction of tissue of intruders that threaten a beehive. However, in honey bees, melittin is not only expressed in the venom gland, but also in other tissues when infected with pathogens. The two venom molecules, melittin and secapin, that are over-expressed in honey bees infected with various pathogens, possibly indicate a role for melittin in the immune response of bees to infectious diseases. Structure Melittin is a small peptide with no disulfide bridge; the ''N''-terminal part of the molecule is predominantly hydrophobic and the ''C''-terminal part is hydrophilic and strongly basic. In water, it forms a tetramer but it also can spontaneously integrate itself into cell membrane ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chagas Disease
Chagas disease, also known as American trypanosomiasis, is a tropical parasitic disease caused by ''Trypanosoma cruzi''. It is spread mostly by insects in the subfamily ''Triatominae'', known as "kissing bugs". The symptoms change over the course of the infection. In the early stage, symptoms are typically either not present or mild, and may include fever, swollen lymph nodes, headaches, or swelling at the site of the bite. After four to eight weeks, untreated individuals enter the chronic phase of disease, which in most cases does not result in further symptoms. Up to 45% of people with chronic infections develop heart disease 10–30 years after the initial illness, which can lead to heart failure. Digestive complications, including an enlarged esophagus or an enlarged colon, may also occur in up to 21% of people, and up to 10% of people may experience nerve damage. is commonly spread to humans and other mammals by the bite of a kissing bug. The disease may also be spr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trypanosoma Cruzi
''Trypanosoma cruzi'' is a species of parasitic euglenoids. Among the protozoa, the trypanosomes characteristically bore tissue in another organism and feed on blood (primarily) and also lymph. This behaviour causes disease or the likelihood of disease that varies with the organism: Chagas disease in humans, dourine and surra in horses, and a brucellosis-like disease in cattle. Parasites need a host body and the haematophagous insect triatomine (descriptions "assassin bug", "cone-nose bug", and "kissing bug") is the major vector in accord with a mechanism of infection. The triatomine likes the nests of vertebrate animals for shelter, where it bites and sucks blood for food. Individual triatomines infected with protozoa from other contact with animals transmit trypanosomes when the triatomine deposits its faeces on the host's skin surface and then bites. Penetration of the infected faeces is further facilitated by the scratching of the bite area by the human or animal host. Life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium In Biology
Calcium ions (Ca2+) contribute to the physiology and biochemistry of organisms' cell (biology), cells. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in contraction of all muscle cell types, and in fertilization. Many enzymes require calcium ions as a Cofactor (biochemistry), cofactor, including several of the coagulation factors. Extracellular calcium is also important for maintaining the potential difference across excitable cell cell membrane, membranes, as well as proper bone formation. Plasma calcium levels in mammals are tightly regulated, electronic-book electronic- with bone acting as the major mineral storage site. Calcium ions, Ca2+, are released from bone into the bloodstream under controlled conditions. Calcium is transported through the bloodstream as dissolved ions or bound to proteins such as serum albumin. Parathyroid hormone secreted by the parathyroid gland regulates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inositol Trisphosphate
Inositol trisphosphate or inositol 1,4,5-trisphosphate abbreviated InsP3 or Ins3P or IP3 is an inositol phosphate signaling molecule. It is made by hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid that is located in the plasma membrane, by phospholipase C (PLC). Together with diacylglycerol (DAG), IP3 is a second messenger molecule used in signal transduction in biological cells. While DAG stays inside the membrane, IP3 is soluble and diffuses through the cell, where it binds to its receptor, which is a calcium channel located in the endoplasmic reticulum. When IP3 binds its receptor, calcium is released into the cytosol, thereby activating various calcium regulated intracellular signals. Properties Chemical formula and molecular weight IP3 is an organic molecule with a molecular mass of 420.10 g/mol. Its empirical formula is C6H15O15P3. It is composed of an inositol ring with three phosphate groups bound at the 1, 4, and 5 carbon positions, and three h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipid
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues was lecith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanosine Triphosphate
Guanosine-5'-triphosphate (GTP) is a purine nucleoside triphosphate. It is one of the building blocks needed for the synthesis of RNA during the transcription process. Its structure is similar to that of the guanosine nucleoside, the only difference being that nucleotides like GTP have phosphates on their ribose sugar. GTP has the guanine nucleobase attached to the 1' carbon of the ribose and it has the triphosphate moiety attached to ribose's 5' carbon. It also has the role of a source of energy or an activator of substrates in metabolic reactions, like that of ATP, but more specific. It is used as a source of energy for protein synthesis and gluconeogenesis. GTP is essential to signal transduction, in particular with G-proteins, in second-messenger mechanisms where it is converted to guanosine diphosphate (GDP) through the action of GTPases. Uses Energy transfer GTP is involved in energy transfer within the cell. For instance, a GTP molecule is generated by one of the enz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
