Figure 5.

A model for the loading of PCNA onto DNA catalyzed by RFC. The RFC subunits that interact with PCNA are indicated in the figure (A and B). Class A subunits can interact with PCNA in the absence of ATP. ATP binding induces a conformational change in RFC that permit the interaction of class B subunits with PCNA. The PCNA ring opens and recloses in response to interactions with the class B subunits governed by ATP binding and hydrolysis. Multiple rounds of ATP binding and hydrolysis may be required before PCNA is finally loaded onto DNA.