Polymerase DNA Directed Sigma (POLs)

One clone (TRF4-1) contained an insert encoding a potential TRF4-related open reading frame of 517 amino acids with a potential initiator methionine at position 41. The sequence included all the regions of high evolutionary conservation in the TRF4 gene family. Saccharomyces cerevisiae and human TRF4-1 are 39% identical over 310 amino acids in the central region of both proteins.

A double mutant in the redundant homologs TRF4 and TRF5 is unable to complete S phase, whereas a TRF4 single mutant completes a presumably defective S phase that results in the failure of cohesion between the replicated sister chromatids. This suggested that TRFs are a key link in the coordination between DNA replication and sister chromatid cohesion.