The Collaboration of Proteins During Replication
Legend:
The major types of proteins, which must work together during the replication
of DNA, are illustrated,
showing their positions.
When DNA replicates, many different proteins work together to accomplish
the following steps:
- The two parent strands are unwound with the help of DNA helicases.
- Single stranded DNA binding proteins attach to the unwound strands,
preventing them from winding back together.
- The strands are held in position, binding easily to DNA polymerase,
which catalyzes the elongation of the leading and lagging strands. (DNA
polymerase also checks the accuracy of its own work!).
- While the DNA polymerase on the leading strand can operate in a continuous
fashion, RNA primer is needed repeatedly on the lagging strand to facilitate
synthesis of Okazaki fragments. DNA primase, which is one of several
polypeptides bound together in a group called primosomes, helps to build
the primer.
- Finally, each new Okazaki fragment is attached to the completed
portion of the lagging strand in a reaction catalyzed by DNA ligase.
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