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DNA polymerase iota; Eta2; RAD30 homolog B (POLI, RAD30B)
Function:
1) error-prone DNA polymerase specifically involved in DNA repair
2) translesion synthesis, where the normal high-fidelity DNA polymerases cannot proceed & DNA synthesis stalls
3) favors Hoogsteen base-pairing in the active site
4) inserts the correct base with high-fidelity opposite an adenosine template
5) low fidelity & efficiency opposite a thymidine template
- will preferentially insert guanosine
6) hypermutation of immunogobulin genes (putative)
7) forms a Schiff base with 5'-deoxyribose phosphate at abasic sites, but may not have lyase activity
8) binds REV1L, POLH
Cofactor: Mg+2
Structure:
- the catalytic core consists of fingers, palm & thumb subdomains, but the fingers & thumb subdomains are much smaller than in high-fidelity polymerases
- residues from five sequence motifs of the Y-family cluster around an active site cleft that can accommodate DNA & nucleotide substrates with relaxed geometric constraints, with consequently higher rates of misincorporation & low processivity
- belongs to the DNA polymerase type-Y family
- contains 1 umuC domain
Compartment:
- nucleus
- accumulates at replication forks after DNA damage
Expression: ubiquitous, highly expressed in testis
General
DNA polymerase
Properties
SIZE: entity length = 740 aa
MW = 83 kD
COMPARTMENT: cell nucleus
MOTIF: UmuC {55-268}
MOTIF: Mg+2-binding site
SITE: 59-59
binding site
SITE: 64-64
FOR-BINDING-OF: deoxy ribonucleotide triphosphate
binding site
SITE: 96-96
FOR-BINDING-OF: deoxy ribonucleotide triphosphate
Mg+2-binding site
SITE: 151-151
glutamate residue {E152}
DNA-binding motif
SITE: 325-332
DNA-binding motif
SITE: 368-386
serine-rich region {589-617}
MOTIF: serine residue (SEVERAL)
Database Correlations
OMIM 605252
UniProt Q9UNA4
PFAM correlations
Entrez Gene 11201
Kegg hsa:11201
ENZYME 2.7.7.7
References
- UniProt :accession Q9UNA4
- NIEHS-SNPs
http://egp.gs.washington.edu/data/poli/