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MAPEG Family
In molecular biology the MAPEG (Membrane-Associated Proteins in Eicosanoid and Glutathione metabolism) family of proteins are a group of membrane associated proteins with highly divergent functions. Included are the 5-lipoxygenase-activating protein (gene FLAP), leukotriene C4 synthase (), which catalyzes the production of leukotriene C4 (LTC4) from leukotriene A4 (LTA4), and microsomal glutathione S-transferase II () (GST-II), which also produces LTC4 from LTA4. Another example is prostaglandin E synthase. This enzyme catalyses the synthesis of PGE2 from PGH2 (produced by cyclooxygenase from arachidonic acid). Because of structural similarities in the active sites of FLAP, LTC4 synthase, and PGE synthase, substrates for each enzyme can compete with one another and modulate synthetic activity. Subfamilies *5-lipoxygenase-activating protein Human proteins containing this domain *5-lipoxygenase-activating protein (ALOX5AP)) * LTC4S * MGST1 *MGST2 Microsomal glutathione S-tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteins
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
5-lipoxygenase-activating Protein
Arachidonate 5-lipoxygenase-activating protein also known as 5-lipoxygenase activating protein, or FLAP, is a protein that in humans is encoded by the ''ALOX5AP'' gene. Function FLAP is necessary for the activation of 5-lipoxygenase and therefore for the production of leukotriene Leukotrienes are a family of eicosanoid inflammatory mediators produced in leukocytes by the oxidation of arachidonic acid (AA) and the essential fatty acid eicosapentaenoic acid (EPA) by the enzyme arachidonate 5-lipoxygenase. Leukotrienes ...s, 5-hydroxyeicosatetraenoic acid, 5-oxo-eicosatetraenoic acid, and specialized pro-resolving mediators of the lipoxin and resolvin classes. It is an integral protein within the nuclear membrane. FLAP is necessary in synthesis of leukotriene, which are lipid mediators of inflammation that is involved in respiratory and cardiovascular diseases. FLAP functions as a membrane anchor for 5-lipooxygenase and as an amine acid-bind protein. How FLAP activate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene C4 Synthase
Leukotriene C4 synthase is an enzyme that in humans is encoded by the ''LTC4S'' gene. The protein encoded by this gene, LTC4S (or glutathione S-transferase II) is an enzyme that converts leukotriene A4 and glutathione to create leukotriene C4. This is a member of MAPEG family of transmembrane proteins. A trimer of Leukotriene C4 synthase is localized on the outer nuclear membrane and endoplasmic reticulum, where it forms a complex with 5-Lipoxygenase-activating protein. This protein is remotely related to microsomal glutathione S-transferase. Function The MAPEG (Membrane-Associated Proteins in Eicosanoid and Glutathione metabolism) family includes a number of human proteins, several of which are involved the production of leukotrienes. This gene encodes an enzyme that catalyzes the first step in the biosynthesis of cysteinyl leukotrienes, potent biological compounds derived from arachidonic acid. Leukotrienes have been implicated as mediators of anaphylaxis and inflammatory ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene C4
Leukotriene C4 (LTC4) is a leukotriene. LTC4 has been extensively studied in the context of allergy and asthma. In cells of myeloid origin such as mast cells, its biosynthesis is orchestrated by translocation to the nuclear envelope along with co-localization of cytosolic phospholipase A2 (cPLA2), Arachidonate 5-lipoxygenase (5-LO), 5-lipoxygenase-activating protein (FLAP) and LTC4 synthase (LTC4S), which couples glutathione to an LTA4 intermediate. The MRP1 transporter then secretes cytosolic LTC4 and cell surface proteases further metabolize it by sequential cleavage of the γ-glutamyl and glycine residues off its glutathione segment, generating the more stable products LTD4 and LTE4. All three leukotrienes then bind at different affinities to two G-protein coupled receptors: CYSLTR1 and CYSLTR2, triggering pulmonary vasoconstriction and bronchoconstriction. In cells of non-haematopoietic lineage, endoplasmic reticulum (ER) stress and chemotherapy induce LTC4 biosynthesi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leukotriene A4
Leukotriene A4 (LTA4) is a leukotriene, and is the precursor for the productions of LTB4 (leukotriene B)) and LTC4 (leukotriene C4). Biosynthesis of Leukotriene A4 Following the biosynthesis of eicosanoid, triggered as a result of infection or inflammation, the resulting arachidonic acid substrate is released from the cell membrane phospholipid will enter the lipooxygenase pathway to produce Leukotriene A4. In this pathway, arachidonic acid is converted into 5-hydroperoxyeicosatetraenoic acid (5-HPETE) as a result of a catalytic complex consisting of the enzyme 5-lipoxygenase (5-LO) and FLAP (5-Lipoxygenase-activating protein) in the presence of ATP and Calcium ions. The resulting 5-HPETE yields the unstable allylic epoxide substrate LTA4 which is quickly hydrolyzed by the LTA4H (Leukotriene A4 hydrolase) enzyme to produce LTB4, or synthesized by LTC4S (Leukotriene C4 synthase) with the addition of glutathione to produce LTC4 which can be further metabolized to produce LTD4 (Le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glutathione S-transferase
Glutathione ''S''-transferases (GSTs), previously known as ligandins, are a family of eukaryotic and prokaryotic phase II metabolic isozymes best known for their ability to catalyze the conjugation of the reduced form of glutathione (GSH) to xenobiotic substrates for the purpose of detoxification. The GST family consists of three superfamilies: the cytosolic, mitochondrial, and microsomal—also known as MAPEG—proteins. Members of the GST superfamily are extremely diverse in amino acid sequence, and a large fraction of the sequences deposited in public databases are of unknown function. The Enzyme Function Initiative (EFI) is using GSTs as a model superfamily to identify new GST functions. GSTs can constitute up to 10% of cytosolic protein in some mammalian organs. GSTs catalyse the conjugation of GSH—via a sulfhydryl group—to electrophilic centers on a wide variety of substrates in order to make the compounds more water-soluble. This activity detoxifies endo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prostaglandin E Synthase
Prostaglandin E synthase (, or PGE synthase) is an enzyme involved in eicosanoid and glutathione metabolism, a member of MAPEG family. It generates prostaglandin E (PGE) from prostaglandin H2. The synthase generating PGE2 is a membrane-associated protein. Isozymes Humans express three prostaglandin-E synthase isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...s, each encoded by a separate gene: References External links * * EC 5.3.99 {{enzyme-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclooxygenase
Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme (specifically, a family of isozymes, ) that is responsible for formation of prostanoids, including thromboxane and prostaglandins such as prostacyclin, from arachidonic acid. A member of the animal-type heme peroxidase family, it is also known as prostaglandin G/H synthase. The specific reaction catalyzed is the conversion from arachidonic acid to prostaglandin H2 via a short-living prostaglandin G2 intermediate. Pharmaceutical inhibition of COX can provide relief from the symptoms of inflammation and pain. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, exert their effects through inhibition of COX. Those that are specific to the COX-2 isozyme are called COX-2 inhibitors. The active metabolite ( AM404) of paracetamol is a COX inhibitor, a fact to which some or all of its therapeutic effect has been attributed. In medicine, the root symbol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arachidonic Acid
Arachidonic acid (AA, sometimes ARA) is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter. Its name derives from the New Latin word ''arachis'' (peanut), but peanut oil does not contain any arachidonic acid. Chemistry In chemical structure, arachidonic acid is a carboxylic acid with a 20-carbon chain and four '' cis''- double bonds; the first double bond is located at the sixth carbon from the omega end. Some chemistry sources define 'arachidonic acid' to designate any of the eicosatetraenoic acids. However, almost all writings in biology, medicine, and nutrition limit the term to ''all cis''-5,8,11,14-eicosatetraenoic acid. Biology Arachidonic acid is a polyunsaturated fatty acid present in the phospholipids (especially phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositides) of membranes of the body's cells, and is abundant in the brain, muscl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LTC4S
Leukotriene C4 synthase is an enzyme that in humans is encoded by the ''LTC4S'' gene. The protein encoded by this gene, LTC4S (or glutathione S-transferase II) is an enzyme that converts leukotriene A4 and glutathione to create leukotriene C4. This is a member of MAPEG family of transmembrane proteins. A trimer of Leukotriene C4 synthase is localized on the outer nuclear membrane and endoplasmic reticulum, where it forms a complex with 5-Lipoxygenase-activating protein. This protein is remotely related to microsomal glutathione S-transferase. Function The MAPEG (Membrane-Associated Proteins in Eicosanoid and Glutathione metabolism) family includes a number of human proteins, several of which are involved the production of leukotrienes. This gene encodes an enzyme that catalyzes the first step in the biosynthesis of cysteinyl leukotrienes, potent biological compounds derived from arachidonic acid. Leukotrienes have been implicated as mediators of anaphylaxis Anaphylaxis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MGST1
Microsomal glutathione S-transferase 1 is an enzyme that in humans is encoded by the ''MGST1'' gene. Function The MAPEG family (Membrane-Associated Proteins in Eicosanoid and Glutathione metabolism) consists of six human proteins, two of which are involved in the production of leukotrienes and prostaglandin E, important mediators of inflammation. Other family members, demonstrating glutathione S-transferase and peroxidase activities, are involved in cellular defense against toxic, carcinogenic, and pharmacologically active electrophilic compounds. This gene encodes a protein that catalyzes the conjugation of glutathione to electrophiles and the reduction of lipid hydroperoxides. This protein is localized to the endoplasmic reticulum and outer mitochondrial membrane where it is thought to protect these membranes from oxidative stress. Four transcript variants of this gene encode one protein isoform A protein isoform, or "protein variant", is a member of a set of highly simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MGST2
Microsomal glutathione S-transferase 2 is an enzyme that in humans is encoded by the ''MGST2'' gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b .... The MAPEG (Membrane-Associated Proteins in Eicosanoid and Glutathione metabolism) family consists of six human proteins, several of which are involved in the production of leukotrienes and prostaglandin E, important mediators of inflammation. This gene encodes a protein that catalyzes the conjugation of leukotriene A4 and reduced glutathione to produce leukotriene C4. References Further reading * * * * * * * * {{gene-4-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
