Polymerase DNA Directed Lambda (POLl)

Pol λ is a member of the X family of DNA polymerases. It is thought to resynthesize missing nucleotides during non-homologous end joining, a pathway of DNA double strand break repair. The crystal structure of pol λ shows that, unlike the DNA polymerases that catalyze DNA replication, pol λ makes extensive contacts with the 5""" phosphate of the downstream DNA strand. This allows the polymerase to stabilize the two ends of a double-strand break and explains how pol λ is uniquely suited for a role in non-homologous end joining. In addition to NHEJ, pol λ can also participate in base excision repair, where it provides backup activity in the absence of Pol β.Besides its catalytic polymerase domain, pol λ has an 8 kDa domain and a BRCT domain.