Simultaneous loss of Rap1 and Cdc13 binding would lead to drastic dysregulation of telomeres. Rap1 binds to the double-stranded part and Cdc13 binds to the single-stranded part of the telomere. In this paper we show that their binding site sequences coincide. The blue bars indicate the three nucleotides that are shared between Rap1 and Cdc13 among those positions of highest importance for their respective binding. If one of these three positions is mutated it would lead to a simultaneous loss of binding for both Rap1 and Cdc13, which would be predicted to have a severe effect on the telomere protection and length regulation.