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| How does the toroidal protein get loaded onto DNA? The clamp loader gp44/62 protein binds to the ring-shaped protein (gp45) (step (c)) and couples the energy from ATP hydrolysis to (presumably) open the ring (step (e)). Next, the gp44/62- gp45 complex binds to DNA at regions where replication can start (step (f)). Last, gp44/62 releases the gp45 ring, which causes the open gp45 to re-close-- around the DNA (step (g)). Thus, the gp44/62 proteins "chaperone" the gp45 ring to the DNA, where it is free to bind the polymerase and stabilize the replication machinery. |
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