Plasmid replication is initiated by the replication initiation factor (REP). This family represents a probable topoisomerase that makes a sequence-specific single-stranded nick in the plasmid DNA at the origin of replication. Human proteins also belong to this family, including myelin transcription factor 2 (Swiss:O15150) and cerebrin-50 (Swiss:Q16301) [2].

1: Nucleotide sequence of the rep gene of staphylococcal plasmid pCW7. Balson DF, Shaw WV; Plasmid 1990;24:74-80. PMID:2270231

2: Cerebrin-50, a human cerebrospinal fluid protein whose mRNA is present in multiple tissues but predominantly expressed in the lymphoblastoid cells and the brain. Li AH, Silvestrini B, Leone MG, Giacomelli S, Cheng CY; Biochem Mol Biol Int 1995;35:135-144. PMID:7735128