This gene encodes the smallest subunit of the replication factor C complex, which consists of five distinct subunits (140, 40, 38, 37, and 36 kDa) and is required for DNA replication. This subunit interacts with the C-terminal region of proliferating cell nuclear antigen and is required to open and load proliferating cell nuclear antigen onto DNA during S phase. It is a member of the AAA+ (ATPases associated with various cellular activities) ATPase family and forms a core complex with the 38 and 40 kDa subunits that possesses DNA-dependent ATPase activity. A related pseudogene has been identified on chromosome 9. Alternative splicing results in multiple transcript variants.