Figure 7. Two parallel pathways for cohesion establishment at the replication fork: chromosome associated cohesin is converted into cohesive structures during S phase.

This process does not require Scc2 (except to load cohesin in the first place), but is strictly dependent on Tof1, Csm3, Chl1, and Ctf4 (the TCCC pathway). A second pathway that operates in parallel is concerned exclusively with de novo loading of cohesin onto nascent DNAs, in a Ctf18-RFC and Scc2-dependent manner (de novo pathway). See Discussion for details.