a large number of proteins that associate with telomere replication forks and validate their importance. We find that POT1 is depleted, whereas histone H1 is specifically enriched, at telomere replication forks. Our work reveals the dynamic changes of the telomeric proteome during replication, providing a valuable resource of telomere replication proteins. To our knowledge, this is the first study that examines the replisome at a specific region of the genome.. Second, the t-loop in which the telomeric 3' overhang is tucked into the double stranded part of the telomeric DNA 16 needs to be unwound during telomere replication by the RTEL1 helicase [17][18][19] .Third, the long noncoding RNA TERRA is transcribed from a large number of chromosome ends [20][21][22][23] . TERRA can form RNA/DNA hybrid structures which interfere with DNA replication if not removed by RNase H, the THO complex, RNA surveillance factors or the splicing factors SFPQ and NONO 24-28 . Finally, replication origins are present in the subtelomeric regions but replication initiates only rarely within the telomeric repeats 14,29 . Therefore, replication at telomeres is mostly !"#$%&#'()* +"#$%&#'()* b c Figure 6