It is vital for effective cell-replication that replication is not stalled at any point by, for instance, damaged bases. Replication termination factor 2 (Rtf2) stabilizes the replication fork stalled at the site-specific replication barrier RTS1 by preventing replication restart until completion of DNA synthesis by a converging replication fork initiated at a flanking origin. The RTS1 element terminates replication forks that are moving in the cen2-distal direction while allowing forks moving in the cen2-proximal direction to pass through the region. Rtf2 contains a C2HC2 motif related to the C3HC4 RING-finger motif, and would appear to fold up, creating a RING finger-like structure but forming only one functional Zn2+ ion-binding site [1]. This domain is also found at the N-terminus of peptidyl-prolyl cis-trans isomerase 4, a divergent cyclophilin family [2].

1: Schizosaccharomyces pombe Rtf2 mediates site-specific replication termination by inhibiting replication restart. Inagawa T, Yamada-Inagawa T, Eydmann T, Mian IS, Wang TS, Dalgaard JZ; Proc Natl Acad Sci U S A. 2009;106:7927-7932. PMID:19416828

2: A divergent multi-domain cyclophilin is highly conserved between parasitic and free-living nematode species and is important in larval muscle development. Page AP, Winter AD; Mol Biochem Parasitol. 1998;95:215-227. PMID:9803414