Chromosome cohesion factor involved in sister chromatid cohesion and fidelity of chromosome transmission. Component of one of the cell nuclear antigen loader complexes, CTF18-replication factor C (CTF18-RFC), which consists of CTF18, CTF8, DSCC1, RFC2, RFC3, RFC4 and RFC5. The CTF18-RFC complex binds to single-stranded and primed DNAs and has weak ATPase activity that is stimulated the presence of primed DNA, replication protein A (RPA) and proliferating cell nuclear antigen (PCNA). The CTF18-RFC complex catalyzes the ATP-dependent loading of PCNA onto primed and gapped DNA. It also interacts with and stimulates POLH, which is suggestive of a protein network that coordinates DNA repair, recombination and chromosome cohesion reactions with replication fork progression (By similarity). Component of the CTF18-RFC complex, which consists of CTF18, CTF8, DSCC1, RFC2, RFC3, RFC4 and RFC5. The CTF18-RFC complex does not interact with the Rad9/Rad1/Hus1 complex. The CTF18-RFC complex interacts with POLH. CTF18/CTF8/DSCC1 associate with PCNA. CTF8 exists as a dimer with DSCC1 (By similarity). Associates with chromatin during S phase. Belongs to the CTF8 family.