DNA polymerase iota

For other uses, see Poli (disambiguation).

DNA polymerase iota is an enzyme that in humans is encoded by the POLI gene.^[4] It is found in higher eukaryotes, and is believed to have arisen from a gene duplication from Pol η. Pol ι, is a Y family polymerase that is involved in translesion synthesis. It can bypass 6-4 pyrimidine adducts and abasic sites and has a high frequency of wrong base incorporation. Like many other Y family polymerases Pol ι, has low processivity, a large DNA binding pocket and doesn't undergo conformational changes when DNA binds. These attributes are what allow Pol ι to carry out its task as a translesion polymerase. Pol ι only uses Hoogsteen base pairing, during DNA synthesis, it will add adenine opposite to thymine in the syn conformation and can add both cytosine and thymine in the anti conformation across guanine, which it flips to the syn conformation.

POLI
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1T3N, 1ZET, 2ALZ, 2DPI, 2DPJ, 2FLL, 2FLN, 2FLP, 2KHU, 2KHW, 2KTF, 2L0G, 2MBB, 3EPG, 3EPI, 3G6X, 3G6Y, 3GV5, 3GV7, 3GV8, 3H40, 3H4B, 3H4D, 3NGD, 3OSN, 3Q8P, 3Q8Q, 3Q8R, 3Q8S, 4EBC, 4EBD, 4EBE, 4EYH, 4EYI, 4FS1, 4FS2
Identifiers
Aliases	POLI, RAD30B, RAD3OB, polymerase (DNA) iota, DNA polymerase iota
External IDs	OMIM: 605252; MGI: 1347081; HomoloGene: 5209; GeneCards: POLI; OMA:POLI - orthologs
Gene location (Mouse) Chr. Chromosome 18 (mouse)[1] Band 18 44.48 cM|18 E2 Start 70,641,751 bp[1] End 70,663,691 bp[1]
RNA expression pattern Bgee Human Mouse (ortholog) n/a Top expressed in seminiferous tubule spermatid zygote spermatocyte blood tail of embryo pituitary gland yolk sac spleen secondary oocyte BioGPS More reference expression data
Gene ontology Molecular function transferase activity damaged DNA binding DNA-directed DNA polymerase activity DNA binding nucleotidyltransferase activity protein binding metal ion binding Cellular component intracellular anatomical structure nucleoplasm nucleus nuclear speck cytoplasmic ribonucleoprotein granule Biological process DNA replication translesion synthesis DNA biosynthetic process DNA repair error-prone translesion synthesis cellular response to DNA damage stimulus Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 11201 26447 Ensembl ENSG00000101751 ENSMUSG00000038425 UniProt Q9UNA4 Q6R3M4 RefSeq (mRNA) NM_007195 NM_001136090 NM_001289515 NM_001289516 NM_011972 RefSeq (protein) NP_009126 NP_001338539 NP_001338540 NP_001338541 NP_001338542 NP_001338543 NP_001338544 NP_001338545 NP_001338546 NP_001338547 NP_001338548 NP_001338549 NP_001338550 NP_001338561 NP_001129562 NP_001276444 NP_001276445 NP_036102 NP_001390096 NP_001390097 NP_001390098 NP_001390102 NP_001390103 NP_001390104 NP_001390106 NP_001390108 NP_001390112 NP_001390118 Location (UCSC) n/a Chr 18: 70.64 – 70.66 Mb PubMed search [2] [3]
Wikidata
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Xeroderma pigmentosum variant

Xeroderma pigmentosum variant (XPV) cells lack DNA polymerase eta (η).^[5] Instead these cells use DNA polymerase iota (ι).^[5] Exposure of XPV cells to UV light causes a very high frequency and unique spectrum of UV-induced mutations that can ultimately lead to malignant transformation.^[5]