The subunits of this heteropentamer are named Rfc1, Rfc2, Rfc3, Rfc4, and Rfc5 (in S. cerevisiae). RFC is used in eukaryotic replication as a clamp loader, similar to the γ Complex in E. coli. Its role as clamp loader involves catalysing the loading of PCNA on to DNA. It binds to the 3' end of the DNA and uses ATP to open the ring of PCNA so that it can encircle the DNA. ATP hydrolysis causes release of RFC, with concomitant clamp loading onto DNA.