This domain is found at the C-terminal end of Telomerase reverse transcriptase (TERT), a ribonucleoprotein enzyme essential for the replication of chromosome termini in most eukaryotes. This entry represents the C-terminal extension (also known as the thumb domain), which forms an all helical bundle. There are three conserved motifs in this domain involved in nucleic acid binding. In humans, single mutations localised within this portion of telomerase are associated with several bone marrow failure syndromes [1,2].

1: Structural Analysis Reveals the Deleterious Effects of Telomerase Mutations in Bone Marrow Failure Syndromes. Hoffman H, Rice C, Skordalakes E; J Biol Chem. 2017;292:4593-4601. PMID:28154186

2: Structure of human telomerase holoenzyme with bound telomeric DNA. Ghanim GE, Fountain AJ, van Roon AM, Rangan R, Das R, Collins K, Nguyen THD; Nature. 2021;593:449-453. PMID:33883742