Pol IV, also known as Pol kappa, DinB, and Dpo4, is a translesion synthesis (TLS) polymerase. Translesion synthesis is a process that allows the bypass of a variety of DNA lesions. TLS polymerases lack proofreading activity and have low fidelity and low processivity. They use damaged DNA as templates and insert nucleotides opposite the lesions. Known primarily as Pol IV in prokaryotes and Pol kappa in eukaryotes, this polymerase has a propensity for generating frameshift mutations. The eukaryotic Pol kappa differs from Pol IV and Dpo4 by an N-terminal extension of ~75 residues known as the "N-clasp" region. The structure of Pol kappa shows DNA that is almost totally encircled by Pol kappa, with the N-clasp region augmenting the interactions between DNA and the polymerase. Pol kappa is more resistant than Pol eta and Pol iota to bulky guanine adducts and is efficient at catalyzing the incorporation of dCTP. Bacterial pol IV has a higher error rate than other Y-family polymerases.
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