DNA Polymerase I (or Pol I) is an enzyme that participates in the process of DNA replication. Discovered by Arthur Kornberg in 1956, it was the first known DNA polymerase (and, indeed, the first known of any kind of polymerase). It was initially characterized in E. coli and is ubiquitous in prokaryotes. In E. coli and many other bacteria, the gene that encodes Pol I is known as polA. The E. coli form of the enzyme is composed of 928 amino acids, and is an example of a processive enzyme—it can sequentially catalyze multiple polymerisations.