Fig. 1.

Evolution of TERT across the Animal kingdom. Phylogenetic tree of TERT sequences from representative metazoan phyla, early-branching metazoans and unicellular relatives of metazoans constructed using the maximum-likelihood method. Bootstrap support percentages from 1000 replicates are labelled at the nodes. Scale bar denotes substitutions per site. Branches that contained less than 30% boostrap replicates were collapsed. Full list of species used and accession numbers can be obtained from Additional file 1: Table S2. Figure inset shows a schematic diagram of the canonical telomerase enzyme bound to the telomeric DNA substrate and the telomerase RNA template. The domain structure of TERT is also shown: the TEN domain with the GQ motif, the TRBD domain with the CP, QFP and T motifs, the RT domain with the 1, 2, A, B′, C, D and E motifs, the N-terminal linker and the CTE region