Replication factor C (RFC) complexes act as loaders or unloaders of the proliferating cell nuclear antigen (PCNA) (or related sliding clamp complexes) during DNA replication- and/or repair-linked processes. The classic RFC1-RFC complex (comprising RFC1 and four smaller subunits, RFC2-5) and Ctf18-RFC (in which RFC1 is substituted with Ctf1 and two other smaller proteins) fundamentally function as PCNA loaders. Rad17-RFC (in which RFC1 is substituted with Rad17) loads the PCNA-like hetero-trimeric 9-1-1 complex at damaged DNA sites. On the other hand, Elg1-RFC (in which RFC1 is substituted for Elg1) functions as a PCNA unloader, removing PCNA from chromatin after DNA synthesis. RFC1-5, Ctf1, Rad17 and Elg1 belong to the AAA+ ATPase family. (Adapted from PMID:28134787.)