Isoform G2P plays an essential role in viral DNA replication; it binds to the origin of replication and cleaves the dsDNA replicative form I (RFI) and becomes covalently bound to it via phosphotyrosine bond, generating the dsDNA replicative form II (RFII).

1: Plasmids carrying cloned fragments of RF DNA from the filamentous phage (phi)Lf can be integrated into the host chromosome via site-specific integration and homologous recombination. Lin NT, Chang RY, Lee SJ, Tseng YH; Mol Genet Genomics. 2001;266:425-435. PMID:11713672