Subunit of the replication factor C (RFC) complex which acts during elongation of primed DNA templates by DNA polymerases delta and epsilon, and is necessary for ATP-dependent loading of proliferating cell nuclear antigen (PCNA) onto primed DNA (PubMed:9488738). This subunit binds to the primer-template junction. Binds the PO-B transcription element as well as other GA rich DNA sequences. Can bind single- or double-stranded DNA. {ECO:0000269|PubMed:8999859, ECO:0000269|PubMed:9488738}. This is the function of Ensembl gene identifier ENSG00000035928 (RFC1, replication factor C subunit 1).