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Polymerase (DNA directed), gamma
Available structures
PDB Ortholog search: PDBe, RCSB
External IDs OMIM174763 MGI1196389 HomoloGene2016 ChEMBL: 2732 GeneCards: POLG Gene
EC number
RNA expression pattern
PBB GE POLG 203366 at tn.png
PBB GE POLG 217635 s at tn.png
More reference expression data
Species Human Mouse
Entrez 5428 18975
Ensembl ENSG00000140521 ENSMUSG00000039176
UniProt P54098 P54099
RefSeq (mRNA) NM_001126131 NM_017462
RefSeq (protein) NP_001119603 NP_059490
Location (UCSC) Chr 15:
89.86 – 89.88 Mb
Chr 7:
79.45 – 79.47 Mb
PubMed search [1] [2]

DNA polymerase subunit gamma is an enzyme that in humans is encoded by the POLG gene.[1]


POLG (alias, POLG1 or POLGa) is the gene that codes for the catalytic subunit of the mitochondrial DNA polymerase, called DNA polymerase gamma.[2] The human POLG cDNA and gene were originally cloned mapped to chromosome 15, 15,q25.[3] In eukaryotic cells, the mitochondrial DNA is replicated by DNA polymerase gamma, a trimeric protein complex composed of a catalytic subunit of 140 kDa encoded by the POLG gene and a dimeric accessory subunit of 55 kDa encoded by the POLG2 gene.[4] The catalytic subunit contains three enzymatic activities, a DNA polymerase activity, a 3’-5’ exonuclease activity that proofreads misincorporated nucleotides, and a 5’-dRP lyase activity required for base excision repair.


Mutations in the POLG gene are associated with several mitochondrial diseases, including Alpers' disease, ataxia-neuropathy disorders, and dominant and recessive forms of progressive external ophthalmoplegia. A list of lists all published mutations in the POLG coding region and their associated disease can be found at the Human DNA Polymerase Gamma Mutation Database.


  1. ^ Zullo SJ, Butler L, Zahorchak RJ, Macville M, Wilkes C, Merril CR (Mar 1998). "Localization by fluorescence in situ hybridization (FISH) of human mitochondrial polymerase gamma (POLG) to human chromosome band 15q24→q26, and of mouse mitochondrial polymerase gamma (Polg) to mouse chromosome band 7E, with confirmation by direct sequence analysis of bacterial artificial chromosomes (BACs)". Cytogenet Cell Genet 78 (3–4): 281–4. doi:10.1159/000134672. PMID 9465903. 
  2. ^ Entrez Gene: POLG polymerase (DNA directed), gamma, catalytic subunit
  3. ^ Ropp, PA, Copeland, WC (1996). "Cloning and characterization of the human mitochondrial DNA polymerase, DNA polymerase gamma". Genomics 36 (3): 449–58. doi:10.1006/geno.1996.0490. PMID 8884268. 
  4. ^ Graziewicz, MA, Longley, MJ, Copeland, WC (2006). "DNA polymerase gamma in mitochondrial DNA replication and repair.". Chem. Rev. 106 (2): 383–405. doi:10.1021/cr040463d. PMID 16464011. 

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