DNA polymerase iota; Eta2; RAD30 homolog B (POLI, RAD30B)

Function

• error-prone DNA polymerase specifically involved in DNA repair
• translesion synthesis, where the normal high-fidelity DNA polymerases cannot proceed & DNA synthesis stalls
• favors Hoogsteen base-pairing in the active site
• inserts the correct base with high-fidelity opposite an adenosine template
• low fidelity & efficiency opposite a thymidine template
  • will preferentially insert guanosine
• hypermutation of immunogobulin genes (putative)
• forms a Schiff base with 5'-deoxyribose phosphate at abasic sites, but may not have lyase activity
• 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

More general terms

• DNA polymerase

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=11201
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:11201
• OMIM: https://mirror.omim.org/entry/605252
• UniProt: http://www.uniprot.org/uniprot/Q9UNA4.html