Cloning and characterisation of the chicken gene encoding the telomeric protein TRF2

The telomere-associated protein TRF2 binds as a homodimer to double-stranded (TTAGGG)n arrays in vitro and localises to chromosome ends in vivo. Inhibition of TRF2 in human cell lines and recent electron microscopy analyses suggest that TRF2 plays a crucial role in the maintenance of telomere integrity. To study the role of TRF2 in vertebrate telomere biology using an alternative model system, we report the isolation and characterisation of the chicken TRF2 locus. The TRF2 protein is highly conserved between mammals and birds, particularly within the dimerisation and myb-type DNA binding domains. However, the chicken ORF predicts an additional protein domain consisting of 15 copies of a degenerate 13 amino acid repeat. Indirect immunofluorescence reveals the localisation of a FLAG-tagged version of the chicken TRF2 protein at chromosome ends in both chicken and human cells suggesting that the protein is functionally conserved.