View source for Phosphoglycerate kinase

{{enzyme
| Name = Phosphoglycerate kinase
| EC_number = 2.7.2.3
| CAS_number = 9001-83-6
| IUBMB_EC_number = 2/7/2/3
| GO_code = 0004618
| image = Phosphoglycerate_kinase_3PGK.png
| width = 
| caption = 
}}

{{Pfam_box
| Symbol = PGK
| Name = Phosphoglycerate kinase
| image = PDB 3pgk EBI.jpg
| width =
| caption = Structure of yeast phosphoglycerate kinase.<ref name="pmid6765200">{{cite journal | vauthors = Watson HC, Walker NP, Shaw PJ, Bryant TN, Wendell PL, Fothergill LA, Perkins RE, Conroy SC, Dobson MJ, Tuite MF | title = Sequence and structure of yeast phosphoglycerate kinase | journal = The EMBO Journal | volume = 1 | issue = 12 | pages = 1635–40 | year = 1982 | pmid = 6765200 | pmc = 553262 | doi =  }}</ref>
| Pfam= PF00162
| InterPro= IPR001576
| SMART=
| Prosite = PDOC00102
| SCOP = 3pgk
| TCDB =
| OPM family=
| OPM protein=
}}

'''Phosphoglycerate kinase''' ({{EC number|2.7.2.3}}) (PGK 1) is an [[enzyme]] that catalyzes the [[Reversible reaction|reversible]] transfer of a phosphate group from [[1,3-bisphosphoglycerate]] (1,3-BPG) to [[Adenosine diphosphate|ADP]] producing [[3-phosphoglycerate]] (3-PG) and [[Adenosine triphosphate|ATP]] :

:1,3-bisphosphoglycerate + ADP {{eqm}} glycerate 3-phosphate + ATP

Like all [[kinase]]s it is a [[transferase]]. PGK is a major enzyme used in [[glycolysis]], in the first ATP-generating step of the glycolytic pathway. In [[gluconeogenesis]], the reaction catalyzed by PGK proceeds in the opposite direction, generating ADP and 1,3-BPG.

In humans, two [[isozymes]] of PGK have been so far identified, [[PGK1]] and PGK2. The isozymes have 87-88% identical [[amino acid]] sequence identity and though they are structurally and functionally similar, they have different localizations: PGK2, encoded by an [[autosomal]] gene, is unique to meiotic and postmeiotic [[spermatogenic]] cells, while PGK1, encoded on the [[X-chromosome]], is ubiquitously expressed in all cells.<ref name="Chiarelli2012 "/>

==Biological function==
[[File:Glycolytic and gluconeogenic pathways.jpg|thumb|left|Diagram showing glycolytic and gluconeogenic pathways. Note that phosphoglycerate kinase is used in both directions.]]

PGK is present in all living organisms as one of the two ATP-generating enzymes in glycolysis. In the gluconeogenic pathway, PGK catalyzes the reverse reaction. Under biochemical [[standard conditions]], the glycolytic direction is favored.<ref name="pmid6765200" />

In the [[Calvin cycle]] in [[photosynthetic]] organisms, PGK catalyzes the phosphorylation of 3-PG, producing 1,3-BPG and ADP, as part of the reactions that regenerate [[ribulose-1,5-bisphosphate]].

PGK has been reported to exhibit thiol [[reductase]] activity on [[plasmin]], leading to [[angiostatin]] formation, which inhibits [[angiogenesis]] and [[tumor]] growth. The enzyme was also shown to participate in [[DNA replication]] and repair in mammal cell [[Cell nucleus|nuclei]].<ref name=Hogg>{{cite journal | vauthors = Lay AJ, Jiang XM, Kisker O, Flynn E, Underwood A, Condron R, Hogg PJ | title = Phosphoglycerate kinase acts in tumour angiogenesis as a disulphide reductase | journal = Nature | volume = 408 | issue = 6814 | pages = 869–73 | date = December 2000 | pmid = 11130727 | doi = 10.1038/35048596 }}</ref>

The human isozyme PGK2, which is only expressed during spermatogenesis, was shown to be essential for sperm function in mice.<ref>{{cite journal | vauthors = Danshina PV, Geyer CB, Dai Q, Goulding EH, Willis WD, Kitto GB, McCarrey JR, Eddy EM, O'Brien DA | title = Phosphoglycerate kinase 2 (PGK2) is essential for sperm function and male fertility in mice | journal = Biology of Reproduction | volume = 82 | issue = 1 | pages = 136–45 | date = Jan 2010 | pmid = 19759366 | doi = 10.1095/biolreprod.109.079699 | url = http://www.biolreprod.org/content/82/1/136.full | pmc=2802118}}</ref>

===Interactive pathway map===
{{GlycolysisGluconeogenesis_WP534|highlight=Phosphoglycerate_kinase}}

== Structure==
===Overview===
PGK is found in all living organisms and its sequence has been [[conserved sequence|highly conserved]] throughout evolution. The enzyme exists as a 415-[[amino acid|residue]] [[monomer]] containing two nearly equal-sized domains that correspond to the N- and C-termini of the protein.<ref name="Dhar">{{cite journal | vauthors = Dhar A, Samiotakis A, Ebbinghaus S, Nienhaus L, Homouz D, Gruebele M, Cheung MS | title = Structure, function, and folding of phosphoglycerate kinase are strongly perturbed by macromolecular crowding | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 107 | issue = 41 | pages = 17586–91 | date = October 2010 | pmid = 20921368 | doi = 10.1073/pnas.1006760107 | pmc=2955104}}</ref>  3-phosphoglycerate (3-PG) binds to the N-terminal, while the nucleotide substrates, MgATP or MgADP, bind to the C-terminal domain of the enzyme. This extended two-domain structure is associated with large-scale 'hinge-bending' conformational changes, similar to those found in [[hexokinase]].<ref name="pmid10593256">{{cite journal | vauthors = Kumar S, Ma B, Tsai CJ, Wolfson H, Nussinov R | title = Folding funnels and conformational transitions via hinge-bending motions | journal = Cell Biochemistry and Biophysics | volume = 31 | issue = 2 | pages = 141–64 | year = 1999 | pmid = 10593256 | doi = 10.1007/BF02738169 }}</ref> The two domains of the protein are separated by a cleft and linked by two [[alpha-helices]].<ref name="Chiarelli2012 "/> At the core of each domain is a 6-stranded parallel [[beta-sheet]] surrounded by alpha helices. The two lobes are capable of folding independently, consistent with the presence of intermediates on the [[Protein folding|folding pathway]] with a single domain folded.<ref name="pmid2124145">{{cite journal | vauthors = Yon JM, Desmadril M, Betton JM, Minard P, Ballery N, Missiakas D, Gaillard-Miran S, Perahia D, Mouawad L | title = Flexibility and folding of phosphoglycerate kinase | journal = Biochimie | volume = 72 | issue = 6-7 | pages = 417–29 | year = 1990 | pmid = 2124145 | doi = 10.1016/0300-9084(90)90066-p }}</ref><ref name=Zerrad11>{{cite journal | vauthors = Zerrad L, Merli A, Schröder GF, Varga A, Gráczer É, Pernot P, Round A, Vas M, Bowler MW | title = A spring-loaded release mechanism regulates domain movement and catalysis in phosphoglycerate kinase | journal = The Journal of Biological Chemistry | volume = 286 | issue = 16 | pages = 14040–8 | date = April 2011 | pmid = 21349853 | pmc = 3077604 | doi = 10.1074/jbc.M110.206813 }}</ref> Though the binding of either substrate triggers a [[conformational change]], only through the binding of both substrates does domain closure occur, leading to the transfer of the phosphate group.<ref name="Chiarelli2012 "/>

The enzyme has a tendency to exist in the open conformation with short periods of closure and catalysis, which allow for rapid [[diffusion]] of substrate and products through the binding sites; the open conformation of PGK is more conformationally stable due to the exposure of a [[hydrophobic]] region of the protein upon domain closure.<ref name="pmid2124145" />

===Role of magnesium===
[[Magnesium]] ions are normally complexed to the phosphate groups the nucleotide substrates of PGK. It is known that in the absence of magnesium, no enzyme activity occurs.<ref name=Varga>{{cite journal | vauthors = Varga A, Palmai Z, Gugolya Z, Gráczer É, Vonderviszt F, Závodszky P, Balog E, Vas M | title = Importance of aspartate residues in balancing the flexibility and fine-tuning the catalysis of human 3-phosphoglycerate kinase | journal = Biochemistry | volume = 51 | issue = 51 | pages = 10197–207 | date = December 2012 | pmid = 23231058 | doi = 10.1021/bi301194t }}</ref> The [[bivalent (chemistry)|bivalent]] metal assists the enzyme [[ligands]] in shielding the bound phosphate group's negative charges, allowing the [[nucleophilic attack]] to occur; this charge-stabilization is a typical characteristic of phosphotransfer reaction.<ref>{{cite journal | vauthors = Cliff MJ, Bowler MW, Varga A, Marston JP, Szabó J, Hounslow AM, Baxter NJ, Blackburn GM, Vas M, Waltho JP | title = Transition state analogue structures of human phosphoglycerate kinase establish the importance of charge balance in catalysis | journal = Journal of the American Chemical Society | volume = 132 | issue = 18 | pages = 6507–16 | date = May 2010 | pmid = 20397725 | doi = 10.1021/ja100974t  }}</ref>  It is theorized that the ion may also encourage domain closure when PGK has bound both substrates.<ref name=Varga />

== Mechanism ==
[[File:PGK Mechanism.jpg|thumb|Phosphoglycerate kinase mechanism in glycolysis.]]
Without either substrate bound, PGK exists in an "open" [[Conformational change|conformation]]. After both the triose and nucleotide substrates are bound to the N- and C-terminal domains, respectively, an extensive hinge-bending motion occurs, bringing the domains and their bound substrates into close proximity and leading to a "closed" conformation.<ref>{{cite journal|last=Banks|first=R. D.|author2=Blake, C. C. F. |author3=Evans, P. R. |author4=Haser, R. |author5=Rice, D. W. |author6=Hardy, G. W. |author7=Merrett, M. |author8= Phillips, A. W. |title=Sequence, structure and activity of phosphoglycerate kinase: a possible hinge-bending enzyme|journal=Nature|date=28 June 1979|volume=279|issue=5716|pages=773–777|doi=10.1038/279773a0}}</ref>  Then, in the case of the forward glycolytic reaction, the beta-phosphate of ADP initiates a [[nucleophilic attack]] on the 1-phosphate of 1,3-BPG. The Lys219 on the enzyme guides the phosphate group to the substrate.

PGK proceeds through a charge-stabilized [[transition state]] that is favored over the arrangement of the bound substrate in the closed enzyme because in the transition state, all three phosphate oxygens are stabilized by [[ligands]], as opposed to only two stabilized oxygens in the initial bound state.<ref>{{cite journal | vauthors = Bernstein BE, Hol WG | title = Crystal structures of substrates and products bound to the phosphoglycerate kinase active site reveal the catalytic mechanism | journal = Biochemistry | volume = 37 | issue = 13 | pages = 4429–36 | date = March 1998 | pmid = 9521762 | doi = 10.1021/bi9724117 }}</ref>

In the [[glycolytic]] pathyway, [[1,3-BPG]] is the [[phosphate]] donor and has a high phosphoryl-transfer potential. The PGK-catalyzed transfer of the phosphate group from 1,3-BPG to ADP to yield ATP can power the carbon-oxidation reaction of the previous glycolytic step (converting [[glyceraldehyde 3-phosphate]] to [[3-phosphoglycerate]]).

== Regulation ==
The enzyme is activated by low concentrations of various multivalent anions, such as pyrophosphate, sulfate, phosphate, and citrate. High concentrations of MgATP and 3-PG activates PGK, while Mg2+ at high concentrations non-competitively inhibits the enzyme.<ref name=LarssonR-1967>{{cite journal | vauthors = Larsson-Raźnikiewicz M | title = Kinetic studies on the reaction catalyzed by phosphoglycerate kinase. II. The kinetic relationships between 3-phosphoglycerate, MgATP2-and activating metal ion | journal = Biochimica et Biophysica Acta | volume = 132 | issue = 1 | pages = 33–40 | date = Jan 1967 | pmid = 6030358 | doi = 10.1016/0005-2744(67)90189-1 }}</ref>

PGK exhibits a wide specificity toward nucleotide substrates.<ref name=Varga_nuc>{{cite journal | vauthors = Varga A, Chaloin L, Sági G, Sendula R, Gráczer E, Liliom K, Závodszky P, Lionne C, Vas M | title = Nucleotide promiscuity of 3-phosphoglycerate kinase is in focus: implications for the design of better anti-HIV analogues | journal = Molecular bioSystems | volume = 7 | issue = 6 | pages = 1863–73 | date = June 2011 | pmid = 21505655 | doi = 10.1039/c1mb05051f }}</ref>  Its activity is inhibited by salicylates, which appear to mimic the enzyme's nucleotide substrate.<ref>{{cite journal|last=Larsson-Raźnikiewicz|first=Märtha|author2=Wiksell, Eva|title=Inhibition of phosphoglycerate kinase by salicylates|journal=Biochimica et Biophysica Acta (BBA) - Enzymology|date=1 March 1978|volume=523|issue=1|pages=94–100|doi=10.1016/0005-2744(78)90012-8}}</ref>

Macromolecular crowding has been shown to increase PGK activity in both computer simluations and [[in vitro]] environments simulating a cell interior; as a result of crowding, the enzyme becomes more enyzmatically active and more compact.<ref name="Dhar" />

== Disease relevance ==
[[Phosphoglycerate kinase deficiency|Phosphoglycerate kinase (PGK) deficiency]] is an X-linked recessive trait associated with [[hemolytic anemia]], [[mental disorders]] and [[myopathy]] in humans,<ref name="pmid6689547">{{cite journal | vauthors = Yoshida A, Tani K | title = Phosphoglycerate kinase abnormalities: functional, structural and genomic aspects | journal = Biomedica Biochimica Acta | volume = 42 | issue = 11-12 | pages = S263-7 | year = 1983 | pmid = 6689547 | doi =  }}</ref><ref name="Beutler2006">{{cite journal | vauthors = Beutler E | title = PGK deficiency | journal = British Journal of Haematology | volume = 136 | issue = 1 | pages = 3–11 | date = Jan 2007 | pmid = 17222195 | doi = 10.1111/j.1365-2141.2006.06351.x }}</ref> depending on form – there exits a hemolytic form and a myopathic form.<ref>[https://ghr.nlm.nih.gov/condition/phosphoglycerate-kinase-deficiency NIH Genetics Home Reference]</ref> Since the trait is X-linked, it is usually fully expressed in males, who have one X chromosome; affected females are typically asymptomatic.<ref name="Chiarelli2012 "/><ref name="Beutler2006" /> The condition results from [[mutations]] in Pgk1, the gene encoding PGK1, and twenty mutations have been identified.<ref name="Beutler2006" /><ref name=Chiarelli2012 /> On a molecular level, the mutation in Pgk1 impairs the thermal stability and inhibits the catalytic activity of the enzyme.<ref name=Chiarelli2012>{{cite journal | vauthors = Chiarelli LR, Morera SM, Bianchi P, Fermo E, Zanella A, Galizzi A, Valentini G | title = Molecular insights on pathogenic effects of mutations causing phosphoglycerate kinase deficiency | journal = PLOS ONE | volume = 7 | issue = 2 | pages = e32065 | year = 2012 | pmid = 22348148 | pmc = 3279470 | doi = 10.1371/journal.pone.0032065 }}</ref>  PGK is the only enzyme in the immediate glycolytic pathway encoded by an X-linked gene. In the case of hemolytic anemia, PGK deficiency occurs in the [[erythrocytes]]. Currently, no definitive treatment exists for PGK deficiency.<ref name=Rhodes_bone_marrow>{{cite journal | vauthors = Rhodes M, Ashford L, Manes B, Calder C, Domm J, Frangoul H | title = Bone marrow transplantation in phosphoglycerate kinase (PGK) deficiency | journal = British Journal of Haematology | volume = 152 | issue = 4 | pages = 500–2 | date = February 2011 | pmid = 21223252 | doi = 10.1111/j.1365-2141.2010.08474.x }}</ref>

PGK1 overexpression has been associated with [[gastric cancer]] and has been found to increase the invasiveness of gastric cancer cells [[in vitro]].<ref>{{cite journal | vauthors = Zieker D, Königsrainer I, Tritschler I, Löffler M, Beckert S, Traub F, Nieselt K, Bühler S, Weller M, Gaedcke J, Taichman RS, Northoff H, Brücher BL, Königsrainer A | title = Phosphoglycerate kinase 1 a promoting enzyme for peritoneal dissemination in gastric cancer | journal = International Journal of Cancer | volume = 126 | issue = 6 | pages = 1513–20 | date = March 2010 | pmid = 19688824 | doi = 10.1002/ijc.24835 | pmc=2811232}}</ref> The enzyme is secreted by [[tumor]] cells and participates in the angiogenic process, leading to the release of [[angiostatin]] and the inhibition of tumor blood vessel growth.<ref name=Hogg /><ref name="Hogg"/>

Due to its wide specificity towards [[nucleotide]] substrates, PGK is known to participate in the phosphorylation and activation of [[HIV]] [[antiretroviral drugs]], which are nucleotide-based.<ref name=Varga_nuc /><ref>{{cite journal | vauthors = Gallois-Montbrun S, Faraj A, Seclaman E, Sommadossi JP, Deville-Bonne D, Véron M | title = Broad specificity of human phosphoglycerate kinase for antiviral nucleoside analogs | journal = Biochemical Pharmacology | volume = 68 | issue = 9 | pages = 1749–56 | date = November 2004 | pmid = 15450940 | doi = 10.1016/j.bcp.2004.06.012 }}</ref>

== Human isozymes ==
{|
|{{Infobox protein
| Name = phosphoglycerate kinase 1
| caption = 
| image = 
| width = 
| HGNCid = 8896
| Symbol = PGK1
| AltSymbols = 
| EntrezGene = 5230
| OMIM = 311800
| RefSeq = NM_000291
| UniProt = P00558
| PDB = 
| ECnumber = 2.7.2.3
| Chromosome = X
| Arm = q
| Band = 13.3
| LocusSupplementaryData = 
}}
|{{Infobox protein
| Name = phosphoglycerate kinase 2
| caption = 
| image = 
| width = 
| HGNCid = 8898
| Symbol = PGK2
| AltSymbols = 
| EntrezGene = 5232
| OMIM = 172270
| RefSeq = NM_138733
| UniProt = P07205
| PDB = 
| ECnumber = 2.7.2.3
| Chromosome = 6
| Arm = p
| Band = 21
| LocusSupplementaryData = -q12
}}
|}

== References ==
{{reflist|30em}}

== External links ==
* {{MeshName|Phosphoglycerate+kinase}}
* [http://www.biochem.arizona.edu/classes/bioc462/462a/NOTES/ENZYMES/pgk.html Illustration at arizona.edu]

{{InterPro content|IPR001576}}

{{glycolysis}}
{{Glycolysis enzymes}}
{{Kinases}}
{{Enzymes}}
{{Portal bar|Molecular and Cellular Biology|border=no}}
{{Use dmy dates|date=April 2017}}

[[Category:EC 2.7.2]]