Component of the telomerase ribonucleoprotein (RNP) complex that is essential for the replication of chromosome termini. Is a component of the double-stranded telomeric DNA-binding TRF1 complex which is involved in the regulation of telomere length by cis-inhibition of telomerase. Also acts as a single-stranded telomeric DNA-binding protein and thus may act as a downstream effector of the TRF1 complex and may transduce information about telomere maintenance and/or length to the telomere terminus. Component of the shelterin complex (telosome) that is involved in the regulation of telomere length and protection. Shelterin associates with arrays of double-stranded TTAGGG repeats added by telomerase and protects chromosome ends; without its protective activity, telomeres are no longer hidden from the DNA damage surveillance and chromosome ends are inappropriately processed by DNA repair pathways. Binds to two or more telomeric single-stranded 5'-TTAGGG-3' repeats (G-strand) and with high specificity to a minimal telomeric single-stranded 5'-TAGGGTTAG-3' sequence. Binds telomeric single-stranded sequences internally or at proximity of a 3'-end. Its activity is TERT dependent but it does not increase TERT activity by itself. In contrast, the ACD-POT1 heterodimer enhances telomere elongation by increasing telomerase processivity (By similarity). Homodimer or homooligomer. Component of the shelterin complex (telosome) composed of TERF1, TERF2, TINF2, TERF2IP, ACD and POT1. Binds single-stranded telomeric DNA as a monomer. Associated component of the telomerase holoenzyme complex. Found in a complex with TERF1, TINF2 and TNKS1. Interacts with TNKS1. Forms heterodimers with ACD. Identified in a complex with ACD and single-stranded telomeric DNA. Colocalizes with telomeric DNA. Belongs to the telombin family.