Fig. 7. Conceptual models for POT1-TERT interaction in telomere synthesis. (A) Alternatively spliced TERT, TERT-V(I8) [V(I8)], acts to displace POT1A bound to telomeres, and this protein interaction allows TERT to be recruited to telomeres, where it can synthesise DNA repeats. (B) The GQ domain of TERT is hidden within the protein structure and is inaccessible to POT1A interaction. Following signals or modifications that trigger conformational changes of the TERT protein, the GQ domain of TERT become accessible to POT1A and the interaction mediates the recruitment of TERT to telomeres.