The CTF18 complex, composed of RFC1 homolog CHTF18 (CTF18), CHTF8 (CTF8) and DSCC1 (DCC1) binds to RFC2, RFC3, RFC4 and RFC5 to form the evolutionarily conserved heteroheptameric CTF18-RFC complex (CTF18-RFC(7s)), in which the RFC1 subunit of the RFC complex is replaced with the CTF18 complex (Bermudez et al. 2003, Merkle et al. 2003). CHTF18 is able to form a heteropentameric CTF18-RFC complex (CTF18-RFC(5s)) with RFC2, RFC3, RFC4 and RFC5 in the absence of CHTF8 and DSCC1 (Bermudez et al. 2003, Shiomi et al. 2004).