Answer:
Main protein in ending high fidelity in E. Coli is the Tus protein that binds to Ter sequences in order to prevent replication forks from passing through the end region. In the Ter sequences, the Tus protein blocks replication by establishing a close association with a particular G-C base pair.
The main protein in human cells is telomerase, which contains an RNA primer and is required to extend the synthesis of lagging strands in linear chromosomal telomeres.
