WordNet
- supply in great quantities; "Pump money into a project"
- a low-cut shoe without fastenings
- a mechanical device that moves fluid or gas by pressure or suction
- deliver forth; "pump bullets into the dummy"
- draw or pour with a pump
- flow intermittently
- move up and down; "The athlete pumps weights in the gym"
- operate like a pump; move up and down, like a handle or a pedal; "pump the gas pedal"
- question persistently; "She pumped the witnesses for information"
- raise (gases or fluids) with a pump
- a white metallic element that burns with a brilliant light; the fifth most abundant element in the earths crust; an important component of most plants and animals (同)Ca, atomic number 20
PrepTutorEJDIC
- 『ポンプ』 / 《単数形で》ポンプで空気(ガス)を入れること / 《副詞[句]を伴って》〈気体・液体〉‘を'『ポンプで入れる』(『出す』) / …‘から'ポンプで水(など)を除く《+『out』+『名』,+『名』+『out』》 / …‘に'ポンプで空気(など)を満たす《+『up』+『名』,+『名』+『up』》 / (ポンプのハンドルのように)…‘を'上下(前後)に動かす / 《話》(…について)〈人〉‘を'あの手この手で問いただす(聞き出す)《+『名』+『for』(『about』)+『名』》 / 《話》(人に)〈知識など〉‘を'詰め込む《+『名』+『into』+『名』〈人〉》;(人から)〈情報など〉‘を'引き出す《+『名』+『out of』+『名』〈人〉》 / ポンプを使う / (ポンプのように)上下に動く,鼓動する / 〈水が〉噴出する
- パンプス(ひもや金具がなく,甲のあいた靴)
- 『カルシウム』(金属元素;化学記号は『Ca』)
Wikipedia preview
出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/10/02 09:21:55」(JST)
[Wiki en表示]
There is a very large transmembrane electrochemical gradient of Ca2+ driving the entry of the ion into cells, yet it is very important for cells to maintain low concentrations of Ca2+ for proper cell signalling; thus it is necessary for the cell to employ ion pumps to remove the Ca2+.[1]
The PMCA and the sodium calcium exchanger (NCX) are together the main regulators of intracellular Ca2+ concentrations.[2]
Contents
- 1 Why cells need calcium pumps
- 2 Muscle cells need calcium pumps
- 3 Understanding calcium pumps through crystallography
- 4 How the calcium pump works
- 5 References
Why cells need calcium pumps
Ca2+ has many important roles as an intracellular messenger. The release of a large amount of free Ca2+ can trigger a fertilized egg to develop, skeletal muscle cells to contract, secretion by secretory cells and interactions with Ca2+ -responsive proteins like calmodulin. To maintain low concentrations of free Ca2+ in the cytosol, cells use membrane pumps like calcium ATPase found in the membranes of sarcoplasmic reticulum of skeletal muscle. These pumps are needed to provide the steep electrochemical gradient that allows Ca2+ to rush into the cytosol when a stimulus signal opens the Ca2+ channels in the membrane. The pumps are also necessary to actively pump the Ca2+ back out of the cytoplasm and return the cell to its pre-signal state.[3]
Muscle cells need calcium pumps
An impulse from a motor neuron causes stimulus of a muscle cell by acetylcholine. In response, the muscle cell allows an influx of sodium ions, which then stimulate a muscle impulse. The muscle cell’s sarcoplasmic reticulum responds to this impulse by becoming more permeable to Ca2+. The diffusion of Ca2+ into the muscle fiber’s cytoplasm allows the Ca2+ to bind to the troponin of the muscle’s thin filament. This binding triggers events with the fiber’s filaments that result in a contraction cycle. When the acetylcholine is decomposed, the membrane’s permeability decreases. The calcium ATPase pumps actively transport the Ca2+ back into the sarcoplasmic reticulum starting the events which relax the muscle. [4]
Understanding calcium pumps through crystallography
Experimental work in crystallography done by Chikashi Toyoshima and colleagues provides a model of the calcium ATPase pump found in skeletal muscle sarcoplasmic reticulum. Calcium ATPase is a member of the P-type ATPases that transport ions across a membrane against a concentration gradient. The scientists used microscopy of tubular crystals and 3D microcrystals to study this protein’s structure. The pump has a molecular mass of 110,000, shows three well separated cytoplasmic domains, with a transmembrane domain consisting of ten alpha helices, and two transmembrane binding sites for the Ca2+.
| cytosol |
| N nucleotide domain |
| P phosphorylation domain |
| A actuator domain |
| Transmembrane domain M1-M10 alpha helices |
| sarcoplasmic lumen |
[5]
How the calcium pump works
Classical Theory of active transport for P-type ATPases [6]
| E1 → |
(2H+ out, 2Ca2+ in)→ |
E1⋅2Ca2+ → |
E1⋅ ATP |
| ↑ |
|
|
↓ |
| E2 |
|
|
E1⋅ADP |
| ↑(Pi out) |
|
|
↓(ADP out) |
| E2⋅Pi |
← E2P |
←(2H+ in, 2Ca2+ out) |
← E1P |
Data from crystallography studies by Chikashi Toyoshima applied to the above cycle [7] [8]
| E1 - high affinity for Ca2+, 2 Ca2+ bound, 2 H+ counter ions released |
| E1⋅2Ca2+ - cytoplasmic gate open, free Ca2+ ion exchange occurs between bound ions and those in cytoplasm, closed configuration of N, P, A domains broken, exposing catalytic site |
| E1⋅ ATP - ATP binds and links N to P, P bends, N contacts A, A causes M1 helix to pull up, closes cytoplasmic gate, bound Ca2+ occluded in transmembrane |
| E1⋅ADP - Phosphoryl transfer, ADP dissociates |
| E1P - A rotates, transmembrane helices rearrange, binding sites destroyed, lumenal gate opened, bound Ca2+ released |
| E2P - open ion pathway to lumen, Ca2+ to lumen |
| E2⋅Pi - A catalyzes release of the Pi, P unbends, transmembrane helices rearranged, closes lumenal gate |
| E2 - transmembrane M1 forms cytoplasmic access tunnel to Ca2+ binding sites |
References
- ^ Carafoli E (January 1991). "Calcium pump of the plasma membrane". Physiol. Rev. 71 (1): 129–53. PMID 1986387.
- ^ Strehler EE, Zacharias DA (January 2001). "Role of alternative splicing in generating isoform diversity among plasma membrane calcium pumps". Physiol. Rev. 81 (1): 21–50. PMID 11152753.
- ^ Bruce Alberts, Essential Cell Biology", third edition,New York, Garland Science, Taylor & Francis Group,LLC, 2010 ISBN 978-0-8153-4129-1, pages 552-553
- ^ David Shier, "Hole's Human Anatomy & Physiology", 12th edition, New York, McGraw-Hill, 2010 ISBN 978-0-07-352570-9, pages 290-293
- ^ Chikashi Toyoshima, 8 June 2000, "Crystal structure of the calcium pump of sarcoplasmic reticulum at 2.6 Å resolution", "Nature", Volume 450, pages 647-654
- ^ Chikashi Toyoshima, "Processing of aspartylphosphate is coupled to lumenal gating of the ion pathway in the calcium pump", The National Academy of Sciences of the USA, online before print December 5, 2007, doi: 10.1073/pnas.0709978104, PNAS December 11, 2007 vol. 104 no. 50 19831-19836,This article contains supporting information online at www.pnas.org/cgi/content/full/0709978104/DC1.
- ^ Chikashi Toyoshima,8 AUGUST 2002,"Changes in the calcium pump accompanying the dissociation of calcium", NATURE, Volume 418,pages 605-611
- ^ Chikashi Toyoshima,29 JULY 2004, "Structure of the calcium pump with a bound ATP analogue", NATURE, Volume 430, pages 529-535
UpToDate Contents
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English Journal
- Diversity of proton pumps in osteoclasts: V-ATPase with a3 and d2 isoforms is a major form in osteoclasts.
- Matsumoto N1, Daido S1, Sun-Wada GH2, Wada Y3, Futai M1, Nakanishi-Matsui M4.
- Biochimica et biophysica acta.Biochim Biophys Acta.2014 Jun;1837(6):744-9. doi: 10.1016/j.bbabio.2014.02.011. Epub 2014 Feb 19.
- Osteoclasts acidify bone resorption lacunae through proton translocation by plasma membrane V-ATPase (vacuolar-type ATPase) which has an a3 isoform, one of the four isoforms of the trans-membrane a subunit (Toyomura et al., J. Biol. Chem., 278, 22023-22030, 2003). d2, a kidney- and epididymis-specif
- PMID 24561225
- Megalencephalic leukoencephalopathy with subcortical cysts protein-1 modulates endosomal pH and protein trafficking in astrocytes: Relevance to MLC disease pathogenesis.
- Brignone MS1, Lanciotti A2, Visentin S3, De Nuccio C4, Molinari P5, Camerini S6, Diociaiuti M7, Petrini S8, Minnone G9, Crescenzi M10, Laudiero LB11, Bertini E12, Petrucci TC13, Ambrosini E14.
- Neurobiology of disease.Neurobiol Dis.2014 Jun;66:1-18. doi: 10.1016/j.nbd.2014.02.003. Epub 2014 Feb 19.
- Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a rare leukodystrophy caused by mutations in the gene encoding MLC1, a membrane protein mainly expressed in astrocytes in the central nervous system. Although MLC1 function is unknown, evidence is emerging that it may regulate ion f
- PMID 24561067
Japanese Journal
- 熱駆動ケミカルヒートポンプにおける冷凍冷熱生成能力向上の検討
- A Study on the Occurrence and Prevention of Perioperative Stroke after Coronary Artery Bypass Grafting
- A Study on the Occurrence and Prevention of Perioperative Stroke after Coronary Artery Bypass Grafting
Related Links
- The calcium pump goes through a cycle of changes in the process of pumping. Four distinct steps have been proposed, and the PDB currently has structures of two of these steps. The structure on the left, from PDB entry 1iwo ,is the ...
- With two calmodulin-binding domains in the calcium pump, the cell can adjust the transportation to be energy efficient, at the same time as being able to quickly reduce the number of calcium ions if the concentration approaches a ...
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- Ca2+ pump、calcium-ATPase、calcium pump、calcium-transporting ATPase、Ca2+-ATPase、Ca2+-transporting ATPase
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カルシウムATPアーゼ、Ca-ATPアーゼ、カルシウムポンプ
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カルシウムポンプ、Ca2+ポンプ
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