The binding of the primer recognition complex involves the loading of the proliferating cell nuclear antigen (PCNA). Replication Factor C (RFC) transiently opens the PCNA toroid in an ATP-dependent reaction, and then allows PCNA to re-close around the double helix adjacent to the primer terminus. This leads to the formation of the "sliding clamp" (Tsurimoto et al. 1990, Mossi and Hubscher 1998). In a human telomere replication model, RFC-mediated PCNA loading increases the processivity of telomeric C-strand synthesis, but does not eliminate polymerase delta stalling on the G-rich template (Lormand et al. 2013).
Interaction of RTEL1 with PCNA is needed for telomere replication and maintenance of telomere integrity (Vannier et al. 2013).