Conserved Telomere Capping Protein 1 (CTC1)

CTC1 interacted with STN1 (OBFC1) and TEN1 in a complex, which the authors called the CST complex. STN1 interacted with both CTC1 and TEN1, but CTC1 and TEN1 did not show significant interaction. The CST complex immunoprecipitated telomeric DNA, but not Alu repeat DNA, from HeLa cells. Only a fraction of telomeres associated with the CST complex, and association of the CST complex with telomeres did not vary during the cell cycle. The CST complex, but not its individual components, bound ssDNA with high affinity and in a sequence-independent manner. The CST complex appeared to protect telomeres independently of POT1. Knockdown studies suggested that the CST complex and POT1 play redundant roles in telomere protection.