Figure 2.

Macromolecular complexes assembled on the DNA at the replication fork. Helicase-primase complex constitutes the so-called primosome that binds the lagging strand DNA, unwinding duplex DNA while it synthesizes RNA primers for the lagging strand polymerase. DNA synthesis on both strands is catalyzed by a holoenzyme complex formed by the polymerase and a processivity β-clamp. The clamp is loaded onto the DNA by the clamp loader complex. The leading and lagging strand holoenzymes interact to form a dimer. Single-stranded DNA resulting from helicase activity is coated with single-stranded DNA-binding protein (SSB).