DNA polymerases catalyse the addition of dNMPs onto the 3-prime ends of DNA chains. There is a general polymerase fold consisting of three subdomains that have been likened to the fingers, palm, and thumb of a right hand. DNA_pol_lambd_f is the central three-helical region of DNA polymerase lambda referred to as the F and G helices of the fingers domain. Contacts with DNA involve this conserved helix-hairpin-helix motif in the fingers region which interacts with the primer strand. This motif is common to several DNA binding proteins and confers a sequence-independent interaction with the DNA backbone [1].

1: A structural solution for the DNA polymerase lambda-dependent repair of DNA gaps with minimal homology. Garcia-Diaz M, Bebenek K, Krahn JM, Blanco L, Kunkel TA, Pedersen LC; Mol Cell. 2004;13:561-572. PMID:14992725