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Arsenite-antimonite Transporter
Arsenite-antimonite transporters are membrane transporters that pump arsenite or antimonite out of a cell. Antimonite is the salt of antimony (Sb(III)) and has been found to significantly impact the toxicity of arsenite. The similar structure of As(III) and Sb(III) makes it plausible that certain transporters function in the efflux of both substrates. Arsenic efflux transporters exist in almost every organism and serve to remove this toxic compound from the cell. Subfamilies As of early 2016, there are at least three known families of proteins known to participate in arsenite and antimonite efflux. * ArsB familyTC# 2.A.45 * ArsAB FamilyTC# 3.A.4 * Arsenical resistance-3 (ARC3) familyTC#2.A.59 The membrane transporter ArsB can function as a secondary carrier or as a primary active transporter, in which case ArsA, an ATPase, must be superimposed onto ArsB. Arsenite and antimonite can also be pumped out of the cell by members of the ARC3 family, a member of the BART superfamil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Membrane Transporter
A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins; that is they exist permanently within and span the membrane across which they transport substances. The proteins may assist in the movement of substances by facilitated diffusion, active transport, osmosis, or reverse diffusion. The two main types of proteins involved in such transport are broadly categorized as either ''channels'' or ''carriers'' (a.k.a. transporters, or permeases). Examples of channel/carrier proteins include the GLUT 1 uniporter, sodium channels, and potassium channels. The solute carriers and atypical SLCs are secondary active or facilitative transporters in humans. Collectively membrane transporters and channels are known as the transportome. Transportomes govern cellular influx and efflux of not only ions and nutrients but drug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenite
In chemistry, an arsenite is a chemical compound containing an arsenic oxyanion where arsenic has oxidation state +3. Note that in fields that commonly deal with groundwater chemistry, arsenite is used generically to identify soluble AsIII anions. IUPAC have recommended that arsenite compounds are to be named as arsenate(III), for example ortho-arsenite is called trioxidoarsenate(III). Ortho-arsenite contrasts to the corresponding anions of the lighter members of group 15, phosphite which has the structure and nitrite, which is bent. A number of different arsenite anions are known: * ortho-arsenite, an ion of arsenous acid, with a pyramidal shape * meta-arsenite, a polymeric chain anion. * pyro-arsenite, * ''catena''-triarsenite, * ''catena''-tetraarsenite, * ''cyclo''-tetraarsenite *, a polymeric anion In all of these the geometry around the AsIII centers are approximately trigonal, the lone pair on the arsenic atom is stereochemically active. Well known examples of arse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antimonite
In chemistry, antimonite refers to a salt of antimony(III), such as NaSb(OH)4 and NaSbO2 (meta-antimonite), which can be prepared by reacting alkali with antimony trioxide, Sb2O3.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier These are formally salts of antimonous acid, Sb(OH)3, whose existence in solution is dubious. Attempts to isolate it generally form Sb2O3·''x''H2O, antimony(III) oxide hydrate, which slowly transforms into Sb2O3. In geology, the mineral stibnite Stibnite, sometimes called antimonite, is a sulfide mineral, a mineral form of antimony trisulfide ( Sb2 S3). It is a soft, metallic grey crystalline solid with an orthorhombic space group. It is the most important source for the metalloid an ..., Sb2S3, is sometimes called antimonite. Antimonites can be compared to antimonates, which contain antimony in the +5 oxidation state. References Antimony(III) compounds Pnictogen oxyanions {{inorganic-compound-stub th:สตà ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ArsB And ArsAB Transporters
Arsenite resistance (Ars) efflux pumps of bacteria may consist of two proteins, ArsBTC# 2.A.45.1.1 the integral membrane constituent with twelve transmembrane spanners) and ArsATC# 3.A.4.1.1 the ATP-hydrolyzing, transport energizing subunit, as for the chromosomally-encoded ''E. coli'' system), or of one protein (just the ArsB integral membrane protein of the plasmid-encoded ''Staphylococcus'' system). ArsA proteins have two ATP binding domains and probably arose by a tandem gene duplication event. ArsB proteins all possess twelve transmembrane spanners and may also have arisen by a tandem gene duplication event. Structurally, the Ars pumps resemble ABC-type efflux pumps, but there is no significant sequence similarity between the Ars and ABC pumps. When only ArsB is present, the system operates by a pmf-dependent mechanism, and consequently belongs in TC subclass 2.A (i.eTC# 2.A.45. When ArsA is also present, ATP hydrolysis drives efflux, and consequently the system belongs in T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BART Superfamily
The Bile/Arsenite/Riboflavin Transporter (BART) superfamily is a superfamily of ubiquitous transport proteins. As of early 2016, the superfamily contains seven established families.Mansour, N.M., Sawhney, M., Tamang, D.G., Vogl, C., Saier, M.H. Jr. 2007. The bile-arsenite-riboflavin transporter (BART) superfamily FEBS Journal 274(3):612-29. Functional data for members of all of these families are available. The seven families are in the Transporter Classification Database The Transporter Classification Database (or TCDB) is an International Union of Biochemistry and Molecular Biology (IUBMB)-approved classification system for membrane transport proteins, including ion channels. Classification The upper level of cla ... with the following TC numbers, names and abbreviations include: *TC# 2.A.10- The 2-Keto-3-Deoxygluconate Transporter (KdgT) Family *TC# 2.A.28- The Bile Acid:Na+ Symporter (BASS) Family *TC# 2.A.59- The Arsenical Resistance-3 (ACR3) Family *TC# 2.A.69- The Auxin Effl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP Hydrolysis
ATP hydrolysis is the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released after splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi). ADP can be further hydrolyzed to give energy, adenosine monophosphate (AMP), and another inorganic phosphate (Pi). ATP hydrolysis is the final link between the energy derived from food or sunlight and useful work such as muscle contraction, the establishment of electrochemical gradients across membranes, and biosynthetic processes necessary to maintain life. Anhydridic bonds are often labelled as "''high-energy bonds"''. P-O bonds are in fact fairly strong (~30 kJ/mol stronger than C-N bonds) Darwent, B. deB. (1970). "Bond Dissociation Energies in Simple Molecules", Nat. Stand. Ref. Data Ser., Nat. Bur. Stand. (U.S.) 31, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenic Toxicity
Arsenic poisoning (or arsenicosis) is a medical condition that occurs due to elevated levels of arsenic in the body. If arsenic poisoning occurs over a brief period of time, symptoms may include vomiting, abdominal pain, encephalopathy, and watery diarrhea that contains blood. Long-term exposure can result in thickening of the skin, darker skin, abdominal pain, diarrhea, heart disease, numbness, and cancer. The most common reason for long-term exposure is contaminated drinking water. Groundwater most often becomes contaminated naturally; however, contamination may also occur from mining or agriculture. It may also be found in the soil and air. Recommended levels in water are less than 10–50 μg/L (10–50 parts per billion). Other routes of exposure include toxic waste sites and pseudo-medicine. Most cases of poisoning are accidental. Arsenic acts by changing the functioning of around 200 enzymes. Diagnosis is by testing the urine, blood, or hair. Prevention is by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arsenite-transporting ATPase
In enzymology, an arsenite-transporting ATPase () is an enzyme that catalyzes the chemical reaction :ATP + H2O + arsenitein \rightleftharpoons ADP + phosphate + arseniteout The 3 substrates of this enzyme are ATP, H2O, and arsenite, whereas its 3 products are ADP, phosphate, and arsenite. This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides acting on acid anhydrides to catalyse transmembrane movement of substances. The systematic name of this enzyme class is ATP phosphohydrolase (arsenite-exporting). Structural studies As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and . See also * Arsenite-Antimonite efflux Arsenite-antimonite transporters are membrane transporters that pump arsenite or antimonite out of a cell. Antimonite is the salt of antimony (Sb(III)) and has been found to significantly impact the toxicity of arsenite. The similar structure of As( ... References * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solute Carrier Family
The solute carrier (SLC) group of membrane transport proteins include over 400 members organized into 66 families. Most members of the SLC group are located in the cell membrane. The SLC gene nomenclature system was originally proposed by the HUGO Gene Nomenclature Committee (HGNC) and is the basis for the official HGNC names of the genes that encode these transporters. A more general transmembrane transporter classification can be found in TCDB, TCDB database. Solutes that are transported by the various SLC group members are extremely diverse and include both charged and uncharged organic molecules as well as inorganic ions and the gas Ammonia transporter, ammonia. As is typical of integral membrane proteins, SLCs contain a number of hydrophobic transmembrane Alpha helix, alpha helices connected to each other by hydrophilic intra- and extra-cellular loops. Depending on the SLC, these transporters are functional as either monomers or obligate homo- or hetero-oligomers. Many SLC fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Transport
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, with energy. Active transport is essential for various physiological processes, such as nutrient uptake, hormone secretion, and nig impulse transmission. For example, the sodium-potassium pump uses ATP to pump sodium ions out of the cell and potassium ions into the cell, maintaining a concentration gradient essential for cellular function. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ATP-binding Cassette Transporter
The ABC transporters, ATP synthase (ATP)-binding cassette transporters are a transport system superfamily that is one of the largest and possibly one of the oldest gene family, gene families. It is represented in all extant taxon, extant Phylum, phyla, from prokaryotes to humans. ABC transporters belong to translocases. ABC transporters often consist of multiple subunits, one or two of which are transmembrane proteins and one or two of which are membrane-associated AAA proteins, AAA ATPases. The ATPase subunits utilize the energy of adenosine triphosphate (ATP) binding and hydrolysis to provide the energy needed for the translocation of substrates across membranes, either for uptake or for export of the substrate. Most of the uptake systems also have an extracytoplasmic receptor, a solute binding protein. Some homologous ATPases function in non-transport-related processes such as RNA translation, translation of RNA and DNA repair. ABC transporters are considered to be an ABC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
