Binding of the polymerase alpha complex and the CST (Ctc1-Stn1-Ten1) complex to the telomeric DNA ends inhibits further extension of the G-strand by telomerase. The loading of the DNA polymerase alpha to telomeres does not depend on the CST complex, but the CST complex is needed for cessation of telomerase activity and for synthesis of RNA primers by the primase component of the DNA polymerase alpha (Feng et al. 2018. Gu et al. 2018).