GGCX
Identifiers
AliasesGGCX, VKCFD1, gamma-glutamyl carboxylase, Gamma-glutamyl carboxylase; GGCX
External IDsOMIM: 137167 MGI: 1927655 HomoloGene: 639 GeneCards: GGCX
Orthologs
SpeciesHumanMouse
Entrez

2677

56316

Ensembl

ENSG00000115486

ENSMUSG00000053460

UniProt

P38435

Q9QYC7

RefSeq (mRNA)

NM_000821
NM_001142269
NM_001311312

NM_019802

RefSeq (protein)

NP_000812
NP_001135741
NP_001298241

NP_062776

Location (UCSC)Chr 2: 85.54 – 85.56 Mbn/a
PubMed search[2][3]
Wikidata
View/Edit HumanView/Edit Mouse

Gamma-glutamyl carboxylase is an enzyme that in humans is encoded by the GGCX gene, located on chromosome 2 at 2p12.[4]

Function

Gamma-glutamyl carboxylase is an enzyme that catalyzes the posttranslational modification of vitamin K-dependent proteins. Many of these vitamin K-dependent proteins are involved in coagulation so the function of the encoded enzyme is essential for hemostasis.[5] Most gla domain-containing proteins depend on this carboxylation reaction for posttranslational modification.[6] In humans, the gamma-glutamyl carboxylase enzyme is most highly expressed in the liver.

Catalytic reaction

Gamma-glutamyl carboxylase oxidizes Vitamin K hydroquinone to Vitamin K 2,3 epoxide, while simultaneously adding CO2 to protein-bound glutamic acid (abbreviation = Glu) to form gamma-carboxyglutamic acid (also called gamma-carboxyglutamate, abbreviation = Gla). Presence of two carboxylate groups causes chelation of Ca2+ , resulting in change in tertiary structure of protein and its activation. The carboxylation reaction will only proceed if the carboxylase enzyme is able to oxidize vitamin K hydroquinone to vitamin K epoxide at the same time; the carboxylation and epoxidation reactions are said to be coupled reactions.[7][8]

a [protein]-α-L-glutamate (Glu) + phylloquinol (KH
2
) + CO
2
+ oxygen → a [protein] 4-carboxy-L-glutamate (Gla) + vitamin K 2,3-epoxide (KO) + H+
+ H
2
O

No experimental structure is known for GGCX, limiting understanding of its reaction mechanism. Based on the fact that the two reactions are coupled, a computational study is able to propose how the reactants interact with each other to form the products.[9] Lys228 has been shown to be the residue responsible for starting the reaction.[10] How the enzyme holds the reactants in place to have them interact with each other remains poorly shown. 491-507 and 395-401 are probably responsible for propeptide and glutamate binding respectively.[11]

Clinical significance

Mutations in this gene are associated with vitamin K-dependent coagulation defect and PXE-like disorder with multiple coagulation factor deficiency.[5][12]

See also

References

  1. 1 2 3 GRCh38: Ensembl release 89: ENSG00000115486 - Ensembl, May 2017
  2. "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  3. "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. Wu SM, Cheung WF, Frazier D, Stafford DW (December 1991). "Cloning and expression of the cDNA for human gamma-glutamyl carboxylase". Science. 254 (5038): 1634–6. Bibcode:1991Sci...254.1634W. doi:10.1126/science.1749935. PMID 1749935.
  5. 1 2 "Entrez Gene: GGCX".
  6. Brenner B, Tavori S, Zivelin A, Keller CB, Suttie JW, Tatarsky I, Seligsohn U (August 1990). "Hereditary deficiency of all vitamin K-dependent procoagulants and anticoagulants". Br. J. Haematol. 75 (4): 537–42. doi:10.1111/j.1365-2141.1990.tb07795.x. PMID 2145029. S2CID 24679257.
  7. Suttie JW (1985). "Vitamin K-dependent carboxylase". Annu. Rev. Biochem. 54 (1): 459–77. doi:10.1146/annurev.bi.54.070185.002331. PMID 3896125.
  8. Presnell SR, Stafford DW (2002). "The vitamin K-dependent carboxylase". Thromb. Haemost. 87 (6): 937–46. doi:10.1055/s-0037-1613115. PMID 12083499. S2CID 27634025.
  9. Silva PJ, Ramos MJ (2007). "Reaction mechanism of the vitamin K-dependent glutamate carboxylase: a computational study". J Phys Chem B. 111 (44): 12883–7. doi:10.1021/jp0738208. PMID 17935315.
  10. Rishavy MA, Hallgren KW, Yakubenko AV, Shtofman RL, Runge KW, Berkner KL (7 November 2006). "Brønsted analysis reveals Lys218 as the carboxylase active site base that deprotonates vitamin K hydroquinone to initiate vitamin K-dependent protein carboxylation". Biochemistry. 45 (44): 13239–48. doi:10.1021/bi0609523. PMID 17073445.
  11. Parker CH, Morgan CR, Rand KD, Engen JR, Jorgenson JW, Stafford DW (11 March 2014). "A conformational investigation of propeptide binding to the integral membrane protein γ-glutamyl carboxylase using nanodisc hydrogen exchange mass spectrometry". Biochemistry. 53 (9): 1511–20. doi:10.1021/bi401536m. PMC 3970815. PMID 24512177.
  12. Vanakker OM, Martin L, Gheduzzi D, Leroy BP, Loeys BL, Guerci VI, Matthys D, Terry SF, Coucke PJ, Pasquali-Ronchetti I, De Paepe A (March 2007). "Pseudoxanthoma elasticum-like phenotype with cutis laxa and multiple coagulation factor deficiency represents a separate genetic entity". J. Invest. Dermatol. 127 (3): 581–7. doi:10.1038/sj.jid.5700610. PMID 17110937.

Further reading

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

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