DNA polymerase eta

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Protein POLH PDB 2i5o.png
Available structures
PDB Ortholog search: PDBe RCSB
Aliases POLH, RAD30, RAD30A, XP-V, XPV, DNA polymerase eta, polymerase (DNA) eta
External IDs MGI: 1891457 HomoloGene: 38189 GeneCards: 5429
RNA expression pattern
PBB GE POLH 219380 x at tn.png
More reference expression data
Species Human Mouse
RefSeq (mRNA)



RefSeq (protein)



Location (UCSC) Chr 6: 43.58 – 43.62 Mb Chr 17: 46.17 – 46.2 Mb
PubMed search [1] [2]
View/Edit Human View/Edit Mouse

DNA polymerase eta (Pol η), is a protein that in humans is encoded by the POLH gene.[3][4][5]

DNA polymerase eta is a eukaryotic DNA polymerase involved in the DNA repair by translesion synthesis. The gene encoding DNA polymerase eta is POLH, also known as XPV, because loss of this gene results in the disease xeroderma pigmentosum. Polymerase eta is particularly important for allowing accurate translesion synthesis of DNA damage resulting from ultraviolet radiation or UV.


This gene encodes a member of the Y family of specialized DNA polymerases. It copies undamaged DNA with a lower fidelity than other DNA-directed polymerases. However, it accurately replicates UV-damaged DNA; when thymine dimers are present, this polymerase inserts the complementary nucleotides in the newly synthesized DNA, thereby bypassing the lesion and suppressing the mutagenic effect of UV-induced DNA damage. This polymerase is thought to be involved in hypermutation during immunoglobulin class switch recombination.[3] Mutations in this gene result in XPV, a variant type of xeroderma pigmentosum.[6]

Clinical significance[edit]

Xeroderma pigmentosum (XP) is an autosomal recessive human disease characterized by sunlight sensitivity, cutaneous and ocular deterioration, and premature malignant skin neoplasms after exposure to sunlight. XP has been classified into eight complementation groups, XP-A to XP-G and XP-V. Cells from XP-A to XP-G patients have defects in the process of nucleotide excision repair (NER), which eliminates a wide variety of structurally unrelated lesions, including ultraviolet light (UV)-induced cyclobutane pyrimidine dimers (CPD) and (6-4) photoproducts, as well as certain chemical adducts. The genes and proteins of XP groups A, B, C, D, F and G have been isolated and found to represent some of the subunits of the core NER machinery. In contrast, cells belonging to the eighth group, XP variant (XP-V), are NER-proficient but display abnormal DNA replication, including reduced ability to elongate nascent DNA strands on UV-irradiated DNA. Thus, the XP-V gene product is likely to be involved in the process of DNA replication on damaged DNA known as post-replication repair, but not in NER


POLH has been shown to interact with PCNA.[7]


  1. ^ "Human PubMed Reference:". 
  2. ^ "Mouse PubMed Reference:". 
  3. ^ a b "Entrez Gene: POLH polymerase (DNA directed), eta". 
  4. ^ Masutani C, Kusumoto R, Yamada A, Dohmae N, Yokoi M, Yuasa M, Araki M, Iwai S, Takio K, Hanaoka F (June 1999). "The XPV (xeroderma pigmentosum variant) gene encodes human DNA polymerase eta". Nature. 399 (6737): 700–4. doi:10.1038/21447. PMID 10385124. 
  5. ^ Johnson RE, Kondratick CM, Prakash S, Prakash L (July 1999). "hRAD30 mutations in the variant form of xeroderma pigmentosum". Science. 285 (5425): 263–5. doi:10.1126/science.285.5425.263. PMID 10398605. 
  6. ^ Stary A, Sarasin A (September 2002). "Molecular mechanisms of UV-induced mutations as revealed by the study of DNA polymerase eta in human cells". Res. Microbiol. 153 (7): 441–5. doi:10.1016/S0923-2508(02)01343-8. PMID 12405351. 
  7. ^ Haracska L, Johnson RE, Unk I, Phillips B, Hurwitz J, Prakash L, Prakash S (November 2001). "Physical and functional interactions of human DNA polymerase eta with PCNA". Mol. Cell. Biol. 21 (21): 7199–206. doi:10.1128/MCB.21.21.7199-7206.2001. PMC 99895free to read. PMID 11585903. 

Further reading[edit]

External links[edit]

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