6-phosphofructokinase, liver type (PFKL) is an enzyme that in humans is encoded by the PFKL gene on chromosome 21.[5] This gene encodes the liver (L) isoform of phosphofructokinase-1, an enzyme that catalyzes the conversion of D-fructose 6-phosphate to D-fructose 1,6-bisphosphate, which is a key step in glucose metabolism (glycolysis). This enzyme is a tetramer that may be composed of different subunits encoded by distinct genes in different tissues. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2014][5]

PFKL
Identifiers
AliasesPFKL, ATP-PFK, PFK-B, PFK-L, phosphofructokinase, liver type
External IDsOMIM: 171860; MGI: 97547; HomoloGene: 55668; GeneCards: PFKL; OMA:PFKL - orthologs
Orthologs
SpeciesHumanMouse
Entrez
Ensembl
UniProt
RefSeq (mRNA)

NM_001002021
NM_002626

NM_008826
NM_001358793

RefSeq (protein)

NP_001002021
NP_002617
NP_001002021.2
NP_002617.3

NP_032852
NP_001345722

Location (UCSC)Chr 21: 44.3 – 44.33 MbChr 10: 77.82 – 77.85 Mb
PubMed search[3][4]
Wikidata
View/Edit HumanView/Edit Mouse

Structure

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Gene

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The PFKL mRNA sequence includes 55 nucleotides at the 5' and 515 nucleotides at the 3' noncoding regions, as well as 2,337 nucleotides in the coding region, encoding 779 amino acids. This coding region only shares a 68% similarity between PFKL and the muscle-type PFKM.[6]

Protein

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This 80-kDa protein is one of three subunit types that comprise the five tetrameric PFK isozymes. The liver PFK (PFK-5) contains solely PFKL, while the erythrocyte PFK includes five isozymes composed of different combinations of PFKL and the second subunit type, PFKM.[7][8] The muscle isozyme (PFK-1) is composed solely of PFKM.[7][9][10] These subunits evolved from a common prokaryotic ancestor via gene duplication and mutation events. Generally, the N-terminal of the subunits carries out their catalytic activity while the C-terminal contains allosteric ligand binding sites[11]

Function

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This gene encodes one of three protein subunits of PFK, which are expressed and combined to form the tetrameric PFK in a tissue-specific manner. As a PFK subunit, PFKL is involved in catalyzing the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate. This irreversible reaction serves as the major rate-limiting step of glycolysis.[7][10][11][12] Notably, knockdown of PFKL has been shown to impair glycolysis and promote metabolism via the pentose phosphate pathway. Moreover, PFKL regulates NADPH oxidase activity through the pentose phosphate pathway and according to NADPH levels.[12]

PFKL has also been detected in leukocytes, kidney, and brain.[9]

Clinical significance

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As the erythrocyte PFK is composed of both PFKL and PFKM, this heterogeneic composition is attributed with the differential PFK activity and organ involvement observed in some inherited PFK deficiency states in which myopathy or hemolysis or both can occur, such as glycogenosis type VII (Tarui disease).[7][8]

Overexpression of PFKL has been associated with Down's syndrome (DS) erythrocytes and fibroblasts and attributed with biochemical changes in PFK that enhance its glycolytic function. Moreover, the PFKL gene maps to the triplicated region of chromosome 21 responsible for DS, indicating that this gene, too, has been triplicated.[13]

Interactive pathway map

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Click on genes, proteins and metabolites below to link to respective articles.[§ 1]

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Glycolysis and Gluconeogenesis edit
  1. ^ The interactive pathway map can be edited at WikiPathways: "GlycolysisGluconeogenesis_WP534".

See also

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References

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  1. ^ a b c GRCh38: Ensembl release 89: ENSG00000141959Ensembl, May 2017
  2. ^ a b c GRCm38: Ensembl release 89: ENSMUSG00000020277Ensembl, May 2017
  3. ^ "Human PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  4. ^ "Mouse PubMed Reference:". National Center for Biotechnology Information, U.S. National Library of Medicine.
  5. ^ a b "Entrez Gene: PFKL phosphofructokinase, liver".
  6. ^ Levanon D, Danciger E, Dafni N, Bernstein Y, Elson A, Moens W, Brandeis M, Groner Y (December 1989). "The primary structure of human liver type phosphofructokinase and its comparison with other types of PFK". DNA. 8 (10): 733–43. doi:10.1089/dna.1989.8.733. PMID 2533063.
  7. ^ a b c d Vora S, Seaman C, Durham S, Piomelli S (January 1980). "Isozymes of human phosphofructokinase: identification and subunit structural characterization of a new system". Proceedings of the National Academy of Sciences of the United States of America. 77 (1): 62–6. Bibcode:1980PNAS...77...62V. doi:10.1073/pnas.77.1.62. PMC 348208. PMID 6444721.
  8. ^ a b Vora S, Davidson M, Seaman C, Miranda AF, Noble NA, Tanaka KR, Frenkel EP, Dimauro S (December 1983). "Heterogeneity of the molecular lesions in inherited phosphofructokinase deficiency". The Journal of Clinical Investigation. 72 (6): 1995–2006. doi:10.1172/JCI111164. PMC 437040. PMID 6227635.
  9. ^ a b Koster JF, Slee RG, Van Berkel TJ (April 1980). "Isoenzymes of human phosphofructokinase". Clinica Chimica Acta; International Journal of Clinical Chemistry. 103 (2): 169–73. doi:10.1016/0009-8981(80)90210-7. PMID 6445244.
  10. ^ a b Musumeci O, Bruno C, Mongini T, Rodolico C, Aguennouz M, Barca E, Amati A, Cassandrini D, Serlenga L, Vita G, Toscano A (April 2012). "Clinical features and new molecular findings in muscle phosphofructokinase deficiency (GSD type VII)". Neuromuscular Disorders. 22 (4): 325–30. doi:10.1016/j.nmd.2011.10.022. PMID 22133655. S2CID 20133199.
  11. ^ a b Brüser A, Kirchberger J, Kloos M, Sträter N, Schöneberg T (May 2012). "Functional linkage of adenine nucleotide binding sites in mammalian muscle 6-phosphofructokinase". The Journal of Biological Chemistry. 287 (21): 17546–53. doi:10.1074/jbc.M112.347153. PMC 3366854. PMID 22474333.
  12. ^ a b Graham DB, Becker CE, Doan A, Goel G, Villablanca EJ, Knights D, Mok A, Ng AC, Doench JG, Root DE, Clish CB, Xavier RJ (21 July 2015). "Functional genomics identifies negative regulatory nodes controlling phagocyte oxidative burst". Nature Communications. 6: 7838. Bibcode:2015NatCo...6.7838G. doi:10.1038/ncomms8838. PMC 4518307. PMID 26194095.
  13. ^ Elson A, Bernstein Y, Degani H, Levanon D, Ben-Hur H, Groner Y (March 1992). "Gene dosage and Down's syndrome: metabolic and enzymatic changes in PC12 cells overexpressing transfected human liver-type phosphofructokinase". Somatic Cell and Molecular Genetics. 18 (2): 143–61. doi:10.1007/bf01233161. PMID 1533471. S2CID 38259672.

Further reading

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