DNA replication proteins and their functions

Helicase

Helicase

Unzips the parental double helix at replication forks

Single-strand binding protein

Keeps the two strands of DNA separate and stabilizes the single DNA strand

Topoisomerase

Removes tension in the DNA, unwinds the strand ahead of the replication fork by breaking, swiveling, and rejoining DNA strands

Primase

Synthesizes RNA primers at 5’ of leading strands

Adds an RNA primer at the 5’ end of each Okazaki fragment of the lagging strand

DNA polymerase 3

Uses parental DNA as a template and synthesizes new DNA strands by adding nucleotides to an existing RNA primer or pre-existing DNA strand

DNA polymerase 1

Removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides to 3’ end of adjacent fragment

DNA LIgase

Joins Okazaki fragments of lagging strand

On leading strands it joins 3’ end of DNA that replaces primer to rest of leading strand DNA