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Phosphatase

February 27, 2023

In biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acid monoester into a phosphate ion and an alcohol. Because a phosphatase enzyme catalyzes the hydrolysis of its substrate, it is a subcategory of hydrolases.[1] Phosphatase enzymes are essential to many biological functions, because phosphorylation (e.g. by protein kinases) and dephosphorylation (by phosphatases) serve diverse roles in cellular regulation and signaling.[2] Whereas phosphatases remove phosphate groups from molecules, kinases catalyze the transfer of phosphate groups to molecules from ATP. Together, kinases and phosphatases direct a form of post-translational modification that is essential to the cell's regulatory network.[3]

A ball and stick model of a phosphate anion.

Phosphatase enzymes are not to be confused with phosphorylase enzymes, which catalyze the transfer of a phosphate group from hydrogen phosphate to an acceptor. Due to their prevalence in cellular regulation, phosphatases are an area of interest for pharmaceutical research.[4][5]

Biochemistry

 
The general reaction catalyzed by a phosphatase enzyme

Phosphatases catalyze the hydrolysis of a phosphomonoester, removing a phosphate moiety from the substrate. Water is split in the reaction, with the -OH group attaching to the phosphate ion, and the H+ protonating the hydroxyl group of the other product. The net result of the reaction is the destruction of a phosphomonoester and the creation of both a phosphate ion and a molecule with a free hydroxyl group.[4]

Phosphatases are able to dephosphorylate seemingly different sites on their substrates with great specificity. Identifying the "phosphatase code," that is, the mechanisms and rules that govern substrate recognition for phosphatases, is still a work in progress, but the first comparative analysis of all the protein phosphatases encoded across nine eukaryotic 'phosphatome' genomes is now available.[6] Studies reveal that so called "docking interactions" play a significant role in substrate binding.[3] A phosphatase recognizes and interacts with various motifs (elements of secondary structure) on its substrate; these motifs bind with low affinity to docking sites on the phosphatase, which are not contained within its active site. Although each individual docking interaction is weak, many interactions occur simultaneously, conferring a cumulative effect on binding specificity.[7] Docking interactions can also allosterically regulate phosphatases and thus influence their catalytic activity.[8]

Functions

In contrast to kinases, phosphatase enzymes recognize and catalyze a wider array of substrates and reactions. For example, in humans, Ser/Thr kinases outnumber Ser/Thr phosphatases by a factor of ten.[4] To some extent, this disparity results from incomplete knowledge of the human phosphatome, that is, the complete set of phosphatases expressed in a cell, tissue, or organism.[3] Many phosphatases have yet to be discovered, and for numerous known phosphatases, a substrate has yet to be identified. However, among well-studied phosphatase/kinase pairs, phosphatases exhibit greater variety than their kinase counterparts in both form and function; this may result from the lesser degree of conservation among phosphatases.[4]

 
Calcineurin (PP2B) is a protein phosphatase enzyme involved in immune system function.

Distinctions

Phosphatases should not be confused with phosphorylases, which add phosphate groups.

Enzyme name Enzymes class Reaction Notes
Phosphorylase Transferase
(EC 2.4 and EC 2.7.7) 		A-B + H-OP ⇌ A-OP + H-B transfer group = A = glycosyl- group or
nucleotidyl- group
Phosphatase Hydrolase
(EC 3) 		P-B + H-OH ⇌ P-OH + H-B
Kinase Transferase
(EC 2.7.1-2.7.4) 		P-B + H-A ⇌ P-A + H-B transfer group = P
P = phosphonate group, OP = phosphate group, H-OP or P-OH = inorganic phosphate

Protein phosphatases

Main article: Protein phosphatase

A protein phosphatase is an enzyme that dephosphorylates an amino acid residue of its protein substrate. Whereas protein kinases act as signaling molecules by phosphorylating proteins, phosphatases remove the phosphate group, which is essential if the system of intracellular signaling is to be able to reset for future use. The tandem work of kinases and phosphatases constitute a significant element of the cell's regulatory network.[9] Phosphorylation (and dephosphorylation) is among the most common modes of posttranslational modification in proteins, and it is estimated that, at any given time, up to 30% of all proteins are phosphorylated.[10][11] Two notable protein phosphatases are PP2A and PP2B. PP2A is involved in multiple regulatory processes, such as DNA replication, metabolism, transcription, and development. PP2B, also called calcineurin, is involved in the proliferation of T cells; because of this, it is the target of some drugs that seek to suppress the immune system.[9]

 
Nucleosides and nucleotides differ by one phosphate, which is cleaved from nucleotides by nucleotidases.

Nucleotidases

Main article: Nucleotidase

A nucleotidase is an enzyme that catalyzes the hydrolysis of a nucleotide, forming a nucleoside and a phosphate ion.[12] Nucleotidases are essential for cellular homeostasis, because they are partially responsible for maintaining a balanced ratio of nucleotides to nucleosides.[13] Some nucleotidases function outside the cell, creating nucleosides that can be transported into the cell and used to regenerate nucleotides via salvage pathways.[14] Inside the cell, nucleotidases may help to maintain energy levels under stress conditions. A cell deprived of oxygen and nutrients may catabolize more nucleotides to boost levels of nucleoside triphosphates such as ATP, the primary energy currency of the cell.[15]

In gluconeogenesis

Phosphatases can also act on carbohydrates, such as intermediates in gluconeogenesis. Gluconeogenesis is a biosynthetic pathway wherein glucose is created from noncarbohydrate precursors; the pathway is essential because many tissues can only derive energy from glucose.[9] Two phosphatases, glucose-6-phosphatase and fructose-1,6-bisphosphatase, catalyze irreversible steps in gluconeogenesis.[16][17] Each cleaves a phosphate group from a six-carbon sugar phosphate intermediate.

Classification

Within the larger class of phosphatase, the Enzyme Commission recognizes 104 distinct enzyme families. Phosphatases are classified by substrate specificity and sequence homology in catalytic domains.[3] Despite their classification into over one hundred families, all phosphatases still catalyze the same general hydrolysis reaction.[1]

In in-vitro experiments, phosphatase enzymes seem to recognize many different substrates, and one substrate may be recognized by many different phosphatases. However, when experiments have been carried out in-vivo, phosphatase enzymes have been shown to be incredibly specific.[3] In some cases, a protein phosphatase (i.e. one defined by its recognition of protein substrates) can catalyze the dephosphorylation of nonprotein substrates.[4] Similarly, dual-specificity tyrosine phosphatases can dephosphorylate not only tyrosine residues, but also serine residues. Thus, one phosphatase can exhibit the qualities of multiple phosphatase families.[9]

See also

References

  1. ^ a b "ENZYME: 3.1.3.-". enzyme.expasy.org. Retrieved 2017-02-21.
  2. ^ Liberti, Susanna; Sacco, Francesca; Calderone, Alberto; Perfetto, Livia; Iannuccelli, Marta; Panni, Simona; Santonico, Elena; Palma, Anita; Nardozza, Aurelio P. (2013-01-01). "HuPho: the human phosphatase portal" (PDF). FEBS Journal. 280 (2): 379–387. doi:10.1111/j.1742-4658.2012.08712.x. PMID 22804825.
  3. ^ a b c d e Sacco, Francesca; Perfetto, Livia; Castagnoli, Luisa; Cesareni, Gianni (2012-08-14). "The human phosphatase interactome: An intricate family portrait". FEBS Letters. 586 (17): 2732–2739. doi:10.1016/j.febslet.2012.05.008. PMC 3437441. PMID 22626554.
  4. ^ a b c d e Li, Xun; Wilmanns, Matthias; Thornton, Janet; Köhn, Maja (2013-05-14). "Elucidating Human Phosphatase-Substrate Networks". Science Signaling. 6 (275): rs10. doi:10.1126/scisignal.2003203. PMID 23674824. S2CID 19282957.
  5. ^ Bodenmiller, Bernd; Wanka, Stefanie; Kraft, Claudine; Urban, Jörg; Campbell, David; Pedrioli, Patrick G.; Gerrits, Bertran; Picotti, Paola; Lam, Henry (2010-12-21). "Phosphoproteomic Analysis Reveals Interconnected System-Wide Responses to Perturbations of Kinases and Phosphatases in Yeast". Science Signaling. 3 (153): rs4. doi:10.1126/scisignal.2001182. PMC 3072779. PMID 21177495.
  6. ^ Chen, Mark J.; Dixon, Jack E.; Manning, Gerard (2017-04-11). "Genomics and evolution of protein phosphatases". Sci. Signal. 10 (474): eaag1796. doi:10.1126/scisignal.aag1796. ISSN 1945-0877. PMID 28400531. S2CID 41041971.
  7. ^ Roy, Jagoree; Cyert, Martha S. (2009-12-08). "Cracking the Phosphatase Code: Docking Interactions Determine Substrate Specificity". Science Signaling. 2 (100): re9. doi:10.1126/scisignal.2100re9. PMID 19996458. S2CID 20590354.
  8. ^ Reményi, Attila; Good, Matthew C; Lim, Wendell A (2006-12-01). "Docking interactions in protein kinase and phosphatase networks". Current Opinion in Structural Biology. Catalysis and regulation / Proteins. 16 (6): 676–685. doi:10.1016/j.sbi.2006.10.008. PMID 17079133.
  9. ^ a b c d G., Voet, Judith; W., Pratt, Charlotte (2013-01-01). Fundamentals of biochemistry : life at the molecular level. Wiley. ISBN 9781118129180. OCLC 892195795.
  10. ^ Cohen, Philip (2002-05-01). "The origins of protein phosphorylation". Nature Cell Biology. 4 (5): E127–130. doi:10.1038/ncb0502-e127. ISSN 1465-7392. PMID 11988757. S2CID 29601670.
  11. ^ Tonks, Nicholas K. (2006). "Protein tyrosine phosphatases: from genes, to function, to disease". Nature Reviews Molecular Cell Biology. 7 (11): 833–846. doi:10.1038/nrm2039. PMID 17057753. S2CID 1302726.
  12. ^ "ENZYME entry 3.1.3.31". enzyme.expasy.org. Retrieved 2017-03-21.
  13. ^ Bianchi, V; Pontis, E; Reichard, P (1986). "Interrelations between substrate cycles and de novo synthesis of pyrimidine deoxyribonucleoside triphosphates in 3T6 cells". Proceedings of the National Academy of Sciences of the United States of America. 83 (4): 986–990. Bibcode:1986PNAS...83..986B. doi:10.1073/pnas.83.4.986. PMC 322995. PMID 3456577.
  14. ^ Zimmermann, Herbert; Zebisch, Matthias; Sträter, Norbert (2012-09-01). "Cellular function and molecular structure of ecto-nucleotidases". Purinergic Signalling. 8 (3): 437–502. doi:10.1007/s11302-012-9309-4. ISSN 1573-9538. PMC 3360096. PMID 22555564.
  15. ^ Hunsucker, Sally Anne; Mitchell, Beverly S.; Spychala, Jozef (2005-07-01). "The 5'-nucleotidases as regulators of nucleotide and drug metabolism". Pharmacology & Therapeutics. 107 (1): 1–30. doi:10.1016/j.pharmthera.2005.01.003. ISSN 0163-7258. PMID 15963349.
  16. ^ "ENZYME entry 3.1.3.9". enzyme.expasy.org. Retrieved 2017-03-21.
  17. ^ "ENZYME entry 3.1.3.11". enzyme.expasy.org. Retrieved 2017-03-21.

External links

February 27, 2023
phosphatase, biochemistry, phosphatase, enzyme, that, uses, water, cleave, phosphoric, acid, monoester, into, phosphate, alcohol, because, phosphatase, enzyme, catalyzes, hydrolysis, substrate, subcategory, hydrolases, enzymes, essential, many, biological, fun. In biochemistry a phosphatase is an enzyme that uses water to cleave a phosphoric acid monoester into a phosphate ion and an alcohol Because a phosphatase enzyme catalyzes the hydrolysis of its substrate it is a subcategory of hydrolases 1 Phosphatase enzymes are essential to many biological functions because phosphorylation e g by protein kinases and dephosphorylation by phosphatases serve diverse roles in cellular regulation and signaling 2 Whereas phosphatases remove phosphate groups from molecules kinases catalyze the transfer of phosphate groups to molecules from ATP Together kinases and phosphatases direct a form of post translational modification that is essential to the cell s regulatory network 3 A ball and stick model of a phosphate anion Phosphatase enzymes are not to be confused with phosphorylase enzymes which catalyze the transfer of a phosphate group from hydrogen phosphate to an acceptor Due to their prevalence in cellular regulation phosphatases are an area of interest for pharmaceutical research 4 5 Contents 1 Biochemistry 2 Functions 2 1 Distinctions 2 2 Protein phosphatases 2 3 Nucleotidases 2 4 In gluconeogenesis 3 Classification 4 See also 5 References 6 External linksBiochemistry Edit The general reaction catalyzed by a phosphatase enzyme Phosphatases catalyze the hydrolysis of a phosphomonoester removing a phosphate moiety from the substrate Water is split in the reaction with the OH group attaching to the phosphate ion and the H protonating the hydroxyl group of the other product The net result of the reaction is the destruction of a phosphomonoester and the creation of both a phosphate ion and a molecule with a free hydroxyl group 4 Phosphatases are able to dephosphorylate seemingly different sites on their substrates with great specificity Identifying the phosphatase code that is the mechanisms and rules that govern substrate recognition for phosphatases is still a work in progress but the first comparative analysis of all the protein phosphatases encoded across nine eukaryotic phosphatome genomes is now available 6 Studies reveal that so called docking interactions play a significant role in substrate binding 3 A phosphatase recognizes and interacts with various motifs elements of secondary structure on its substrate these motifs bind with low affinity to docking sites on the phosphatase which are not contained within its active site Although each individual docking interaction is weak many interactions occur simultaneously conferring a cumulative effect on binding specificity 7 Docking interactions can also allosterically regulate phosphatases and thus influence their catalytic activity 8 Functions EditIn contrast to kinases phosphatase enzymes recognize and catalyze a wider array of substrates and reactions For example in humans Ser Thr kinases outnumber Ser Thr phosphatases by a factor of ten 4 To some extent this disparity results from incomplete knowledge of the human phosphatome that is the complete set of phosphatases expressed in a cell tissue or organism 3 Many phosphatases have yet to be discovered and for numerous known phosphatases a substrate has yet to be identified However among well studied phosphatase kinase pairs phosphatases exhibit greater variety than their kinase counterparts in both form and function this may result from the lesser degree of conservation among phosphatases 4 Calcineurin PP2B is a protein phosphatase enzyme involved in immune system function Distinctions Edit Phosphatases should not be confused with phosphorylases which add phosphate groups Enzyme name Enzymes class Reaction NotesPhosphorylase Transferase EC 2 4 and EC 2 7 7 A B H OP A OP H B transfer group A glycosyl group or nucleotidyl groupPhosphatase Hydrolase EC 3 P B H OH P OH H BKinase Transferase EC 2 7 1 2 7 4 P B H A P A H B transfer group PP phosphonate group OP phosphate group H OP or P OH inorganic phosphateProtein phosphatases Edit Main article Protein phosphataseA protein phosphatase is an enzyme that dephosphorylates an amino acid residue of its protein substrate Whereas protein kinases act as signaling molecules by phosphorylating proteins phosphatases remove the phosphate group which is essential if the system of intracellular signaling is to be able to reset for future use The tandem work of kinases and phosphatases constitute a significant element of the cell s regulatory network 9 Phosphorylation and dephosphorylation is among the most common modes of posttranslational modification in proteins and it is estimated that at any given time up to 30 of all proteins are phosphorylated 10 11 Two notable protein phosphatases are PP2A and PP2B PP2A is involved in multiple regulatory processes such as DNA replication metabolism transcription and development PP2B also called calcineurin is involved in the proliferation of T cells because of this it is the target of some drugs that seek to suppress the immune system 9 Nucleosides and nucleotides differ by one phosphate which is cleaved from nucleotides by nucleotidases Nucleotidases Edit Main article Nucleotidase A nucleotidase is an enzyme that catalyzes the hydrolysis of a nucleotide forming a nucleoside and a phosphate ion 12 Nucleotidases are essential for cellular homeostasis because they are partially responsible for maintaining a balanced ratio of nucleotides to nucleosides 13 Some nucleotidases function outside the cell creating nucleosides that can be transported into the cell and used to regenerate nucleotides via salvage pathways 14 Inside the cell nucleotidases may help to maintain energy levels under stress conditions A cell deprived of oxygen and nutrients may catabolize more nucleotides to boost levels of nucleoside triphosphates such as ATP the primary energy currency of the cell 15 In gluconeogenesis Edit Phosphatases can also act on carbohydrates such as intermediates in gluconeogenesis Gluconeogenesis is a biosynthetic pathway wherein glucose is created from noncarbohydrate precursors the pathway is essential because many tissues can only derive energy from glucose 9 Two phosphatases glucose 6 phosphatase and fructose 1 6 bisphosphatase catalyze irreversible steps in gluconeogenesis 16 17 Each cleaves a phosphate group from a six carbon sugar phosphate intermediate Classification EditWithin the larger class of phosphatase the Enzyme Commission recognizes 104 distinct enzyme families Phosphatases are classified by substrate specificity and sequence homology in catalytic domains 3 Despite their classification into over one hundred families all phosphatases still catalyze the same general hydrolysis reaction 1 In in vitro experiments phosphatase enzymes seem to recognize many different substrates and one substrate may be recognized by many different phosphatases However when experiments have been carried out in vivo phosphatase enzymes have been shown to be incredibly specific 3 In some cases a protein phosphatase i e one defined by its recognition of protein substrates can catalyze the dephosphorylation of nonprotein substrates 4 Similarly dual specificity tyrosine phosphatases can dephosphorylate not only tyrosine residues but also serine residues Thus one phosphatase can exhibit the qualities of multiple phosphatase families 9 See also EditAcid phosphatase Alkaline phosphatase Endonuclease Exonuclease phosphatase family Kinase Phosphatome Phosphotransferase Protein phosphatase Protein phosphatase 2 PP2A References Edit a b ENZYME 3 1 3 enzyme expasy org Retrieved 2017 02 21 Liberti Susanna Sacco Francesca Calderone Alberto Perfetto Livia Iannuccelli Marta Panni Simona Santonico Elena Palma Anita Nardozza Aurelio P 2013 01 01 HuPho the human phosphatase portal PDF FEBS Journal 280 2 379 387 doi 10 1111 j 1742 4658 2012 08712 x PMID 22804825 a b c d e Sacco Francesca Perfetto Livia Castagnoli Luisa Cesareni Gianni 2012 08 14 The human phosphatase interactome An intricate family portrait FEBS Letters 586 17 2732 2739 doi 10 1016 j febslet 2012 05 008 PMC 3437441 PMID 22626554 a b c d e Li Xun Wilmanns Matthias Thornton Janet Kohn Maja 2013 05 14 Elucidating Human Phosphatase Substrate Networks Science Signaling 6 275 rs10 doi 10 1126 scisignal 2003203 PMID 23674824 S2CID 19282957 Bodenmiller Bernd Wanka Stefanie Kraft Claudine Urban Jorg Campbell David Pedrioli Patrick G Gerrits Bertran Picotti Paola Lam Henry 2010 12 21 Phosphoproteomic Analysis Reveals Interconnected System Wide Responses to Perturbations of Kinases and Phosphatases in Yeast Science Signaling 3 153 rs4 doi 10 1126 scisignal 2001182 PMC 3072779 PMID 21177495 Chen Mark J Dixon Jack E Manning Gerard 2017 04 11 Genomics and evolution of protein phosphatases Sci Signal 10 474 eaag1796 doi 10 1126 scisignal aag1796 ISSN 1945 0877 PMID 28400531 S2CID 41041971 Roy Jagoree Cyert Martha S 2009 12 08 Cracking the Phosphatase Code Docking Interactions Determine Substrate Specificity Science Signaling 2 100 re9 doi 10 1126 scisignal 2100re9 PMID 19996458 S2CID 20590354 Remenyi Attila Good Matthew C Lim Wendell A 2006 12 01 Docking interactions in protein kinase and phosphatase networks Current Opinion in Structural Biology Catalysis and regulation Proteins 16 6 676 685 doi 10 1016 j sbi 2006 10 008 PMID 17079133 a b c d G Voet Judith W Pratt Charlotte 2013 01 01 Fundamentals of biochemistry life at the molecular level Wiley ISBN 9781118129180 OCLC 892195795 Cohen Philip 2002 05 01 The origins of protein phosphorylation Nature Cell Biology 4 5 E127 130 doi 10 1038 ncb0502 e127 ISSN 1465 7392 PMID 11988757 S2CID 29601670 Tonks Nicholas K 2006 Protein tyrosine phosphatases from genes to function to disease Nature Reviews Molecular Cell Biology 7 11 833 846 doi 10 1038 nrm2039 PMID 17057753 S2CID 1302726 ENZYME entry 3 1 3 31 enzyme expasy org Retrieved 2017 03 21 Bianchi V Pontis E Reichard P 1986 Interrelations between substrate cycles and de novo synthesis of pyrimidine deoxyribonucleoside triphosphates in 3T6 cells Proceedings of the National Academy of Sciences of the United States of America 83 4 986 990 Bibcode 1986PNAS 83 986B doi 10 1073 pnas 83 4 986 PMC 322995 PMID 3456577 Zimmermann Herbert Zebisch Matthias Strater Norbert 2012 09 01 Cellular function and molecular structure of ecto nucleotidases Purinergic Signalling 8 3 437 502 doi 10 1007 s11302 012 9309 4 ISSN 1573 9538 PMC 3360096 PMID 22555564 Hunsucker Sally Anne Mitchell Beverly S Spychala Jozef 2005 07 01 The 5 nucleotidases as regulators of nucleotide and drug metabolism Pharmacology amp Therapeutics 107 1 1 30 doi 10 1016 j pharmthera 2005 01 003 ISSN 0163 7258 PMID 15963349 ENZYME entry 3 1 3 9 enzyme expasy org Retrieved 2017 03 21 ENZYME entry 3 1 3 11 enzyme expasy org Retrieved 2017 03 21 External links EditPhosphatases at the US National Library of Medicine Medical Subject Headings MeSH Portal Biology Retrieved from https en wikipedia org w index php title Phosphatase amp oldid 1134039600, wikipedia, wiki, book, books, library,

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