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. This domain is also found at the N-terminus of peptidyl-prolyl cis-trans isomerase 4, a divergent cyclophilin family.