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Integral Monotopic Protein
Integral monotopic proteins are permanently attached to the cell membrane from one side, and are a type of integral membrane protein (IMP). Three-dimensional structures of the following integral monotopic proteins have been determined: *prostaglandin H2 syntheses 1 and 2 (cyclooxygenases) *lanosterol synthase and squalene-hopene cyclase *microsomal prostaglandin E synthase * carnitine O-palmitoyltransferase 2 * Phosphoglycosyl transferase C There are also structures of integral monotopic ''domains'' of transmembrane proteins: * monoamine oxidases A and B *fatty acid amide hydrolase *mammalian cytochrome P450 oxidase Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...s * corticosteroid 11-beta-dehydrogenases References {{DEFAULTSORT:Integral Monotopic Protein Integral membra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment (the extracellular space). The cell membrane consists of a lipid bilayer, made up of two layers of phospholipids with cholesterols (a lipid component) interspersed between them, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as membrane transporters, and peripheral proteins that loosely attach to the outer (peripheral) side of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose. The cell membrane controls the movement of substances in and out of cells and organelles, being selectively permeable to ions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Integral Membrane Protein
An integral, or intrinsic, membrane protein (IMP) is a type of membrane protein that is permanently attached to the biological membrane. All ''transmembrane proteins'' are IMPs, but not all IMPs are transmembrane proteins. IMPs comprise a significant fraction of the proteins encoded in an organism's genome. Proteins that cross the membrane are surrounded by annular lipids, which are defined as lipids that are in direct contact with a membrane protein. Such proteins can only be separated from the membranes by using detergents, nonpolar solvents, or sometimes denaturing agents. Structure Three-dimensional structures of ~160 different integral membrane proteins have been determined at atomic resolution by X-ray crystallography or nuclear magnetic resonance spectroscopy. They are challenging subjects for study owing to the difficulties associated with extraction and crystallization. In addition, structures of many water-soluble protein domains of IMPs are available in the Prote ... [...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 "COX" is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lanosterol Synthase
Lanosterol synthase () is an oxidosqualene cyclase (OSC) enzyme that converts (S)-2,3-oxidosqualene to a protosterol cation and finally to lanosterol. Lanosterol is a key four-ringed intermediate in cholesterol biosynthesis. In humans, lanosterol synthase is encoded by the LSS gene. In eukaryotes, lanosterol synthase is an integral monotopic protein associated with the cytosolic side of the endoplasmic reticulum. Some evidence suggests that the enzyme is a soluble, non- membrane bound protein in the few prokaryotes that produce it. Due to the enzyme's role in cholesterol biosynthesis, there is interest in lanosterol synthase inhibitors as potential cholesterol-reducing drugs, to complement existing statins. Mechanism Though some data on the mechanism has been obtained by the use of suicide inhibitors, mutagenesis studies, and homology modeling, it is still not fully understood how the enzyme catalyzes the formation of lanosterol. Initial epoxide protonation and ring ope ... [...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] |
Carnitine O-palmitoyltransferase
Carnitine O-palmitoyltransferase (also called carnitine palmitoyltransferase) is a mitochondrial transferase enzyme () involved in the metabolism of palmitoylcarnitine into palmitoyl-CoA. A related transferase is carnitine acyltransferase. Molecules Image:Palmitoylcarnitine.PNG , Palmitoylcarnitine Image:Palmitoyl coenzyme A.svg, Palmitoyl CoA Pathway Human forms There are four different forms of CPT in humans: * CPT1A – associated with Carnitine palmitoyltransferase I deficiency * CPT1B * CPT1C * CPT2 – associated with carnitine palmitoyltransferase II deficiency See also * References External links * – Acyltransferases ChoActase / COT / CPT family in PROSITE Choline/Carnitine o-acyltransferase familyin Pfam Pfam is a database of protein families that includes their annotations and multiple sequence alignments generated using hidden Markov models. The most recent version, Pfam 35.0, was released in November 2021 and contains 19,632 families. Uses ... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undecaprenyl Phosphate N,N'-diacetylbacillosamine 1-phosphate Transferase
Phosphoglycosyl transferase C (PglC) is an enzyme belonging to a class known as monotopic phosphoglycosyl transferases (PGT). PGTs are required for the synthesis of glycoconjugates on the membrane surface of bacteria''.'' Glycoconjugates, such as glycoproteins, are imperative for bacterial communication as well as host cell interactions between prokaryotic and eukaryotic cells lending to bacteria's pathogenicity. Background PglC is found in the pathogenic gram-negative organism ''Campylobacter jejuni'' (''C. jejuni'')''.'' Infection from ''C. jejuni'' results in acute gastroenteritis followed by vomiting, diarrhea, fever and abdominal pain. The most common route of infection is through undercooked poultry as birds are a common source of ''C. jejuni''. Recent studies have also shown an association between prior ''C. jejuni'' infection and the neurological syndrome Guillan-Barré. The glycoconjugates, lipopolysaccharides (LPS), found in the membrane of the bacteria resemble ga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monoamine Oxidase
Monoamine oxidases (MAO) () are a family of enzymes that catalyze the oxidation of monoamines, employing oxygen to clip off their amine group. They are found bound to the outer membrane of mitochondria in most cell types of the body. The first such enzyme was discovered in 1928 by Mary Bernheim in the liver and was named tyramine oxidase. The MAOs belong to the protein family of flavin-containing amine oxidoreductases. MAOs are important in the breakdown of monoamines ingested in food, and also serve to inactivate monoamine neurotransmitters. Because of the latter, they are involved in a number of psychiatric and neurological diseases, some of which can be treated with monoamine oxidase inhibitors (MAOIs) which block the action of MAOs. Subtypes and tissue distribution In humans there are two types of MAO: MAO-A and MAO-B. * Both are found in neurons and astroglia. * Outside the central nervous system: ** MAO-A is also found in the liver, pulmonary vascular endothelium, gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatty Acid Amide Hydrolase
Fatty acid amide hydrolase or FAAH (, oleamide hydrolase, anandamide amidohydrolase) is a member of the serine hydrolase family of enzymes. It was first shown to break down anandamide in 1993. In humans, it is encoded by the gene ''FAAH''.; Function FAAH is an integral membrane hydrolase with a single ''N''-terminal transmembrane domain. ''In vitro'', FAAH has esterase and amidase activity. ''In vivo'', FAAH is the principal catabolic enzyme for a class of bioactive lipids called the fatty acid amides (FAAs). Members of the FAAs include: * Anandamide (''N''-arachidonoylethanolamine), an endocannabinoid * 2-arachidonoylglycerol (2-AG), an endocannabinoid. * Other ''N''-acylethanolamines, such as ''N''-oleoylethanolamine and ''N''-palmitoylethanolamine * The sleep-inducing lipid oleamide * The ''N''-acyltaurines, which are agonists of the transient receptor potential (TRP) family of calcium channels. ''FAAH'' knockout mice display highly elevated (>15-fold) levels of ''N'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome P450 Oxidase
Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compounds, as well as for hormone synthesis and breakdown. In 1963, Estabrook, Cooper, and Rosenthal described the role of CYP as a catalyst in steroid hormone synthesis and drug metabolism. In plants, these proteins are important for the biosynthesis of defensive compounds, fatty acids, and hormones. CYP enzymes have been identified in all kingdoms of life: animals, plants, fungi, protists, bacteria, and archaea, as well as in viruses. However, they are not omnipresent; for example, they have not been found in ''Escherichia coli''. , more than 300,000 distinct CYP proteins are known. CYPs are, in general, the terminal oxidase enzymes in electron transfer chains, broadly categorized as P450-containing systems. The term "P450" is derived fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
