DNA polymerase lambda

DNA polymerase lambda, also known as POLL, is a is_associated_with::protein that, in humans, is encoded by the POLLA is_associated_with::gene.

Function
Pol λ is a member of the X family of is_associated_with::DNA polymerases. It is thought to resynthesize missing nucleotides during is_associated_with::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 is_associated_with::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 is_associated_with::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 is_associated_with::BRCT domain. The 8 kDa domain has lyase activity that can remove a 5' deoxyribosephosphate group from the end of a strand break. The BRCT domain is a phosphopeptide binding domain that is common among DNA repair proteins and is likely involved in coordinating protein-protein interactions. Pol λ is structurally and functionally related to pol μ, another member of the X family that also participates in is_associated_with::non-homologous end joining. Like pol μ, pol λ participates in V(D)J recombination, the process by which B-cell and is_associated_with::T-cell receptor diversity is generated in the is_associated_with::vertebrate is_associated_with::immune system. Whereas pol μ is important for heavy-chain rearrangements, pol λ seems to be more important for light-chain rearrangements. The yeast is_associated_with::Saccharomyces cerevisiae has a single homolog of both pol λ and pol μ called Pol4.

Interactions
Pol λ has been shown to interact with is_associated_with::PCNA.