In Saccharomyces cerevisiae Rif1 interacts with Rif2 and Rap1 to regulate telomere length and establish telomeric silencing []. Despite the protein sequence similarity with yeast Rif1, human Rif1 does not bind to Rap1 and does not accumulate at functional telomeres. Human Rif1 is required for checkpoint mediated arrest of cell cycle progression in response to DNA damage during S-phase (the intra-S-phase checkpoint) and is regulated by ATM and 53BP1 [].
This domain is found in N-terminal of the telomere-associated protein,Rif1. In budding yeast, Rif1 is Recruited to telomeres by interaction with the C terminus of RAP1 is recruited to telomeres by interaction with the C terminus of RAP1 and negatively regulates telomere length by preventing telomere elongation or promoting degradation of the telomere ends [, ]. In mammals, Rif1 is required for checkpoint mediated arrest of cell cycle progression in response to DNA damage during S-phase (the intra-S-phase checkpoint) [].