Telomeric DNA-binding protein, which binds to single-stranded C-rich repeat sequences, with high specificity to the 5'-GCCTAA-3' sequence (PubMed:18329362, PubMed:23390606). Repeat sequence binding can be at the 5' or 3' telomeric end (PubMed:18329362). May have a role in protecting the 5' end of the C-rich strand of the telomere (PubMed:23390606). Acts redundantly with pot-2 to negatively regulate telomerase-mediated telomere extension (PubMed:18329362, PubMed:23390606, PubMed:24297748). Also regulates telomere length by the telomerase-independent telomere maintenance pathway called ALT (alternative lengthening of telomeres) (PubMed:23390606, PubMed:22547822, PubMed:24297748). Through sun-1, anchors telomeres to the nuclear envelope in embryos (PubMed:24297748). More highly expressed in meiotic pachytene nuclei than in diakinesis-stage oocyte nuclei (PubMed:23390606). Also expressed in mitotic nuclei (PubMed:23390606). Expressed in sperm and oocytes. Expressed in embryos. Belongs to the telombin family.