proton ATPase

P-type ATPases form a covalent phosphorylated (hence the symbol ’P') intermediate as part of its reaction cycle. P-type ATPases undergo major conformational changes during the catalytic cycle. P-type ATPases are not evolutionary related to V- and F-type ATPases.

{{Main|Plasma membrane H+-ATPase}}

P-type proton ATPase{{cite journal | vauthors = Goffeau A, Slayman CW | title = The proton-translocating ATPase of the fungal plasma membrane | journal = Biochimica et Biophysica Acta (BBA) - Reviews on Bioenergetics | volume = 639 | issue = 3–4 | pages = 197–223 | date = December 1981 | pmid = 6461354 | doi = 10.1016/0304-4173(81)90010-0 }}{{cite journal | vauthors = Morsomme P, Slayman CW, Goffeau A | title = Mutagenic study of the structure, function and biogenesis of the yeast plasma membrane H(+)-ATPase | journal = Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes | volume = 1469 | issue = 3 | pages = 133–57 | date = November 2000 | pmid = 11063881 | doi = 10.1016/S0304-4157(00)00015-0 }}{{cite journal | vauthors = Palmgren MG | title = PLANT PLASMA MEMBRANE H+-ATPases: Powerhouses for Nutrient Uptake | journal = Annual Review of Plant Physiology and Plant Molecular Biology | volume = 52 | pages = 817–845 | date = June 2001 | pmid = 11337417 | doi = 10.1146/annurev.arplant.52.1.817 }}{{cite journal | vauthors = Morth JP, Pedersen BP, Buch-Pedersen MJ, Andersen JP, Vilsen B, Palmgren MG, Nissen P | title = A structural overview of the plasma membrane Na+,K+-ATPase and H+-ATPase ion pumps | journal = Nature Reviews. Molecular Cell Biology | volume = 12 | issue = 1 | pages = 60–70 | date = January 2011 | pmid = 21179061 | doi = 10.1038/nrm3031 }} (or Plasma membrane H+-ATPase) is found in the plasma membranes of eubacteria, archaea, protozoa, fungi and plants. Here it serves as a functional equivalent to the Na⁺/K⁺ ATPase of animal cells; i.e. it energizes the plasma membrane by forming an electrochemical gradient of protons (Na⁺ in animal cells), that in turn drives secondary active transport processes across the membrane. The plasma membrane H⁺-ATPase is a P3A ATPase with a single polypeptide of 70-100 kDa.

{{Main|Hydrogen potassium ATPase}}

Animals have a gastric hydrogen potassium ATPase or H⁺/K⁺ ATPase that belongs to the P-type ATPase family and functions as an electroneutral proton pump. This pump is found in the plasma membrane of cells in the gastric mucosa and functions to acidify the stomach.{{cite journal | vauthors = Sachs G, Shin JM, Briving C, Wallmark B, Hersey S | title = The pharmacology of the gastric acid pump: the H+,K+ ATPase | journal = Annu Rev Pharmacol Toxicol | volume = 35 | pages = 277–305 |date=1995 | pmid = 7598495 | doi = 10.1146/annurev.pa.35.040195.001425 }} This enzyme is a P2C ATPase, characterized by having a supporting beta-subunit, and is closely related to the Na⁺/K⁺ ATPase.

{{Main|V-ATPase}}

V-type proton ATPase{{cite journal | vauthors = Beyenbach KW, Wieczorek H | title = The V-type H+ ATPase: molecular structure and function, physiological roles and regulation | journal = The Journal of Experimental Biology | volume = 209 | issue = Pt 4 | pages = 577–89 | date = February 2006 | pmid = 16449553 | doi = 10.1242/jeb.02014 | doi-access = free }}{{cite journal | vauthors = Nelson N | title = The vacuolar H(+)-ATPase--one of the most fundamental ion pumps in nature | journal = The Journal of Experimental Biology | volume = 172 | pages = 19–27 | date = November 1992 | pmid = 1337091 | url = http://jeb.biologists.org/cgi/pmidlookup?view=long&pmid=1337091 }}{{cite journal | vauthors = Marshansky V, Rubinstein JL, Grüber G | title = Eukaryotic V-ATPase: novel structural findings and functional insights | journal = Biochimica et Biophysica Acta (BBA) - Bioenergetics | volume = 1837 | issue = 6 | pages = 857–79 | date = June 2014 | pmid = 24508215 | doi = 10.1016/j.bbabio.2014.01.018 | doi-access = free }} (or V-ATPase) translocate protons into intracellular organelles other than mitochondria and chloroplasts, but in certain cell types they are also found in the plasma membrane. V-type ATPases acidify the lumen of the vacuole (hence the symbol 'V') of fungi and plants, and that of the lysosome in animal cells. Furthermore, they are found in endosomes, clathrin coated vesicles, hormone storage granules, secretory granules, Golgi vesicles and in the plasma membrane of a variety of animal cells. Like F-type ATPases, V-type ATPases are composed of multiple subunits and carry out rotary catalysis.{{cite journal | vauthors = Stewart AG, Laming EM, Sobti M, Stock D | title = Rotary ATPases--dynamic molecular machines | journal = Current Opinion in Structural Biology | volume = 25 | pages = 40–8 | date = April 2014 | pmid = 24878343 | doi = 10.1016/j.sbi.2013.11.013 | doi-access = free }} The reaction cycle involves tight binding of ATP but proceeds without formation of a covalent phosphorylated intermediate. V-type ATPases are evolutionary related to F-type ATPases.{{cite journal | vauthors = Mulkidjanian AY, Makarova KS, Galperin MY, Koonin EV | title = Inventing the dynamo machine: the evolution of the F-type and V-type ATPases | journal = Nature Reviews. Microbiology | volume = 5 | issue = 11 | pages = 892–9 | date = November 2007 | pmid = 17938630 | doi = 10.1038/nrmicro1767 }}

{{Main|F-ATPase}}

F-type proton ATPase{{cite journal | vauthors = Boyer PD | title = The ATP synthase--a splendid molecular machine | journal = Annual Review of Biochemistry | volume = 66 | pages = 717–49 | year = 1997 | pmid = 9242922 | doi = 10.1146/annurev.biochem.66.1.717 }}{{cite journal | vauthors = Junge W, Nelson N | title = ATP synthase | journal = Annual Review of Biochemistry | volume = 84 | pages = 631–57 | year = 2015 | pmid = 25839341 | doi = 10.1146/annurev-biochem-060614-034124 | doi-access = free }} (or F-ATPase) typically operates as an ATP synthase that dissipates a proton gradient rather than generating one; i.e. protons flow in the reverse direction compared to V-type ATPases. In eubacteria, F-type ATPases are found in plasma membranes. In eukaryotes, they are found in the mitochondrial inner membranes and in chloroplast thylakoid membranes. Like V-type ATPases, F-type ATPases are composed of multiple subunits and carry out rotary catalysis. The reaction cycle involves tight binding of ATP but proceeds without formation of a covalent phosphorylated intermediate. F-type ATPases are evolutionary related to V-type ATPases.

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{{ATPase}}

{{Acid anhydride hydrolases}}

{{Enzymes}}

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{{DEFAULTSORT:Proton Atpase}}

Category:Transmembrane proteins