Structure of Fission Yeast POT1 Protein

The Pot1 protein of fission yeast has a distinctive groove into which a short length of single-stranded DNA (with the telomeric sequence GGTTAC) binds. The groove is called an oligonucleotide-binding (OB) fold.

When the single-stranded DNA at the end of the chromosome is bound to the OB fold, it is protected from degradation and modification (thus the moniker “protection of telomeres”).