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Encyclopedia > Active transport
Sodium-Potassium pump, an example of Primary active transport
Sodium-Potassium pump, an example of Primary active transport

Active transport (sometimes called active intake because of the absorbing movement of particles) is an energy-requiring process that moves material across a cell membrane and up the concentration gradient. The cell uses active transport in three situations: when a particle is going from low to high concentration, when particles need help entering the membrane because they are selectively impermeable, and when very large particles enter and exit the cell.

Active transport can be:

Primary: Uses the chemical energy from ATP or other sources. ATP may refer to: Chemistry/Biochemistry Adenosine triphosphate, the universal energy currency of all known living organisms Companies Alberta Theatre Projects, a major Canadian theatre company. ...


Secondary: Uses the electrochemical gradient to power transport. When particles are being moved from areas of low concentration to areas of high concentration(ie against the concentration gradient) then specific carrier proteins in the membrane are required to move these particles. the carrier proteins bind to specific molecules(eg glucose) and transport them into the cell where they are released. Energy in the form of ATP is required for this process so this is known as Active TransportItalic text. Examples: sodium is transported out of the cell and potassium into the cell by the sodium/potassium pump, a form of active transport. In cellular biology, an electrochemical gradient refers to the electrical and chemical properties across a membrane. ...


Classes of primary transporters (pumps)

ABC pumps

ABC class pumps transport small molecules across membranes. They are also called the ABC superfamily. They consist of two transmembrane domains, and two ATP binding domains. ABC pumps are involved in the transport of small molecules, phospholipids and lipophilic drugs in mammalian cells. In bacteria they transport amino acids, sugars and peptides.[1] ATP-binding cassette transporters (ABC-transporter) are members of a a superfamily which is one of the largest, and most ancient families with representatives in all extant phyla from prokaryotes to humans. ... Phospholipid Two schematic representations of a phospholipid. ... This article or section does not cite its references or sources. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria For the folk-rock band see The Mammals. ... Look up cell in Wiktionary, the free dictionary. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... This article is about the class of chemicals. ... Peptides (from the Greek πεπτος, digestible), are the family of short molecules formed from the linking, in a defined order, of various α-amino acids. ...

P-type pumps

P-type pumps use ATP to transport ions against a gradient. They are phosphorylated during transport, which is different from the other classes of active transport pumps. This article is about the electrically charged particle. ... Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule. ...

Some examples of P-class pumps are the sodium-potassium pump, proton pump, calcium transport in muscle cells and the hydrogen-potassium pump in the apical membrane of the stomach. The title given to this article is incorrect due to technical limitations. ... Calcium ATPase is a form of ATPase which transfers calcium after a muscle has contracted. ... For other uses of Muscle, see Muscle (disambiguation). ... Gastric hydrogen potassium ATPase also know as H+/K+ ATPase // Function and location The gastric hygrogen potassium ATPase or H+/K+ ATPase is the proton pump of the stomach and as such is the enzyme primarily responsible for the acidification of the stomach contents. ... Alpha intercalated cell The apical membrane of a polarized cell is the part of the plasma membrane that forms its lumenal surface, distinct from the basolateral membrane. ... In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. ...

V-type pumps

A V-Class Proton Pump moves protons from one side of a membrane to the other and uses ATP as the source of energy.
A V-Class Proton Pump moves protons from one side of a membrane to the other and uses ATP as the source of energy.

V-class proton pumps are a type of ATPase. They use the energy released by the hydrolysis of ATP to move protons (or in a few cases of bacteria sodium-ions[2]) against their concentration gradient.[3] All proteins that fall into this class have two structural domains. One domain called the V0 domain is made of 5 subunits and is involved in translocation of the protein. The other domain is called the V1 domain which is composed of 8 subunits and is involved in ATP-hydrolysis.[4] Image File history File links Size of this preview: 450 × 600 pixelsFull resolution‎ (600 × 800 pixels, file size: 178 KB, MIME type: image/png) I made this image in Adobe Illustrator. ... Image File history File links Size of this preview: 450 × 600 pixelsFull resolution‎ (600 × 800 pixels, file size: 178 KB, MIME type: image/png) I made this image in Adobe Illustrator. ... V-ATPase schematic Vacuolar type H+-ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. ... ATPases are a class of enzymes that catalyze the decomposition of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and a free phosphate ion. ... Hydrolysis is a chemical reaction or process in which a chemical compound is broken down by reaction with water. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... For alternative meanings see proton (disambiguation). ... For sodium in the diet, see Salt. ... It has been suggested that Structural domain be merged into this article or section. ... Protein targeting a. ... This is the reaction by which chemical energy that has been stored and transported in the high-energy phosphodiester bonds in ATP is released, for example in the muscles, to produce work. ...

V-class proton pumps are found in a wide variety of organelle membranes. In fungi, yeast and plant cells they are found in Vacuole membranes. In animals they are found in the membranes of lysosomes and endosomes. V-class proton pumps are also found in the plasma membranes of macrophages[5] , osteoclasts[6] , and renal intercalated cells.[7] In cell biology, an organelle is a specialized subunit within a cell that has a specific function, and is separately enclosed within its own lipid membrane. ... Divisions Chytridiomycota Zygomycota Ascomycota Basidiomycota The Fungi (singular: fungus) are a large group of organisms ranked as a kingdom within the Domain Eukaryota. ... Typical divisions Ascomycota (sac fungi) Saccharomycotina (true yeasts) Taphrinomycotina Schizosaccharomycetes (fission yeasts) Basidiomycota (club fungi) Urediniomycetes Sporidiales Yeasts are a growth form of eukaryotic micro organisms classified in the kingdom Fungi, with about 1,500 species described;[1] they dominate fungal diversity in the oceans. ... Plant cell structure Plant cells are eukaryotic cells that differ in several key respects from the cells of other eukaryotic organisms. ... Schematic of typical animal cell, showing subcellular components: (1) nucleolus (2) nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles Vacuoles are found in the cytoplasm of most plant cells and... Various organelles labeled. ... In biology an endosome is a membrane-bound compartment inside cells. ... Macrophages (Greek: big eaters) are cells found in tissues that are responsible for phagocytosis of pathogens, dead cells and cellular debris. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ...

The function of this class of pump is strictly to transport protons across the membrane that they are embedded within. Transporting protons across a membrane can decrease the pH on one side of the membrane which can be critical for organelle functioning.[3] This is indeed the case in endosomes. When endosomes bud off from the plasma membrane as they do in receptor-mediated endocytosis V-class pumps increase the acidity within the lumen of the endosome. This increased acidity acts as a signal to the ligand-receptors to release their ligands which can be molecules such as LDL or insulin. Ligand release is critical so the ligand-receptors can be recycled back to the plasma membrane and join another endosome.[8] Decreasing the pH of endosomes is also important for the entry of some membrane bound viruses. The viral protein haemagglutinin is located on the surface of the Influenza virus and the acidification provided by this protein aids in viral entry.[9] For alternative meanings see proton (disambiguation). ... For other uses, see PH (disambiguation). ... Receptor-mediated endocytosis (RME) is a process by which cells internalize molecules (endocytosis) into a cell by the inward budding of plasma membrane vesicles containing proteins with receptor sites specific to the molecules being internalized. ... For other uses, see acid (disambiguation). ... artery anatomy, showing lumen The lumen (pl. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... In chemistry, a ligand is an atom, ion, or molecule (see also: functional group) that generally donates one or more of its electrons through a coordinate covalent bond to, or shares its electrons through a covalent bond with, one or more central atoms or ions (these ligands act as a... Low-density lipoprotein (LDL) refers to a class and range of lipoprotein particles, varying somewhat in their size and contents, which carry cholesterol in the blood and around the body, for use by various cells. ... Not to be confused with inulin. ... This article is about biological infectious particles. ... Hemagglutinin (HA) is an antigenic glycoprotein found on the surface of the Influenza virus and is responsible for binding the virus to the cell that is being infected. ... Flu redirects here. ...

V-class pumps located in cell membranes which also have critical functions to the cell. In renal intercalated cells these pumps secrete protons into the fluid in the kidneys, helping to maintain an optimal pH in the kidneys.[10] In humans, mutations in the genes coding for this protein can lead to metabolic acidosis;[11] a potentially deadly disease. This article is about modern humans. ... This article is about mutation in biology, for other meanings see: mutation (disambiguation). ... In medicine, metabolic acidosis is a state in which the blood pH is low (under 7. ... This article is about the medical term. ...

F-type proton pumps

Uses H+ gradient in order to produce ATP. Can also work in the reverse direction.

Role in neurons

Image File history File links This is a lossless scalable vector image. ...

See also

Ion channels are pore-forming proteins that help to establish and control the small voltage gradient that exists across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient. ... A symporter, also known as a coporter, is an integral membrane protein that is involved in facilitated diffusion. ... An antiporter is an integral membrane protein that is involved in secondary active transport. ... Passive transport means moving biochemicals and other atomic or molecular substances across membranes. ... Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ...


  1. ^ Lodish et al (2008) Molecular Cell Biology, 6, W. H. Freeman
  2. ^ Murata T, Yamato I, Kakinuma Y, Leslie AG, Walker JE (April 2005). "Structure of the rotor of the V-Type Na+-ATPase from Enterococcus hirae". Science (journal) 308 (5722): 654–9. doi:10.1126/science.1110064. PMID 15802565. 
  3. ^ a b Lodish, Harvey; et al. (2003). Molecular Cell Biology, 5, W. H. Freeman. ISBN 0716743663. 
  4. ^ Nishi, T. "The Vacuolar H+-ATPases - Nature's Most Versatile Proton Pumps". Nature Rev. MCB 3: 94-103. 
  5. ^ Brisseau, G.F.; et al. (1996). "IL-1 increases V-ATPase activity in murine peritoneal macrophages". J. Biol. Chem 271: 2005-2001. 
  6. ^ Li, Y.P.; Y. Liang, E. Li, P. Stashenko (1999). "Atp6i-deficient mice exhibit severe osteopetrosis due to loss of osteoclast-mediated extracellular acidification". Nature Genet. 23: 447-451. 
  7. ^ Brown, D.; S. Breton (2000). "V-ATPase dependent lumenal acidification in the kidney collecting duct and the epididymis/vas deferens". J. Exp. Biol 203: 127-145. 
  8. ^ Forjac, M. (1999). "Structure and Properties of the Vacuolar (H+)-ATPases". J. Biol.. 
  9. ^ Han, X.; Bushweller, J.H., Cafiso, D.S. & Tamm, L.K. (2001). "Membrane structure and fusion-triggering conformational change of the fusion domain from influenza hemagglutinin". Nature Struct. Biol. 8: 715-720. 
  10. ^ Brown, Denniscoauthors=Brenton, Sylvie (2000). "H+V-ATPase-Dependent Luminal Acidification in the Kidney Collecting Duct and Epididymis/Vas Deferens: Vesicle Recycling and Transcytotic Pathways". J. Exp. Biol. 203: 137-145. 
  11. ^ Karet, F.E; et al. (1999). "Mutations in ATP6N1B, encoding a new kidney vacuolar proton pump 116-kD subunit, cause recessive distal renal tubular acidosis with preserved hearing". Nature Genet. 21: 84-90. 
A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... Passive transport means moving biochemicals and other atomic or molecular substances across membranes. ... diffusion (disambiguation). ... facilitated diffusion in cell membrane, showing ion channels and carrier proteins Facilitated diffusion (or facilitated transport) is a process of diffusion, a form of passive transport, where molecules diffuse across membranes, with the assistance of transport proteins. ... Osmosis is the spontaneous net movement of water across a semipermeable membrane from a region of low solute concentration to a solution with a high solute concentration, down a solute concentration gradient. ... example of Primary active transport Primary active transport directly uses energy to transport molecules across a membrane. ... secondary active transport In secondary active transport, in contrast to primary active transport, there is no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of the cell is used. ... Neuron A (transmitting) to neuron B (receiving) 1. ... The degranulation process in a Mast cell. ... Endocytosis (IPA: ) is a process whereby cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. ... Steps of a macrophage ingesting a pathogen: a. ... Transcytosis is the process by which various macromolecules are transported across the interior of a cell. ... Pinocytosis or cell drinking is one of three forms of endocytosis, a cellular process that is used to take up smaller particles in cell by splitting in small particles , and forms vesicles which then merge with lysosomes to hydrolyze (hydrolytic enyzmes) to break down the particles. ... Pinocytosis Non-specific, adsorptive pinocytosis is a form of endocytosis, a process in which small particles are taken in by a cell by splitting off small vesicles from the cell surface. ...

  Results from FactBites:
Transport Across Cell Membranes (2816 words)
Active transport is the pumping of molecules or ions through a membrane against their concentration gradient.
Direct active transport of the ion establishes a concentration gradient.
The Na /glucose transporter is used to actively transport glucose out of the intestine and also out of the kidney tubules and back into the blood.
Active transport - Wikipedia, the free encyclopedia (542 words)
Active transport is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes.
The active transport of small molecules or ions across a cell membrane is generally carried out by transport proteins that are found in the membrane.
In secondary active transport, there is however no direct coupling of ATP; instead, the electrochemical potential difference created by pumping ions out of cells is used.
  More results at FactBites »



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