This is the C-terminal domain of RFC (replication factor-C) protein of the clamp loader complex which binds to the DNA sliding clamp (proliferating cell nuclear antigen, PCNA). The five modules of RFC assemble into a right-handed spiral, which results in only three of the five RFC subunits (RFC-A, RFC-B and RFC-C) making contact with PCNA, leaving a wedge-shaped gap between RFC-E and the PCNA clamp-loader complex. The C-terminal is vital for the correct orientation of RFC-E with respect to RFC-A [1].

1: Structural analysis of a eukaryotic sliding DNA clamp-clamp loader complex. Bowman GD, O'Donnell M, Kuriyan J; Nature. 2004;429:724-730. PMID:15201901