Association between Primase and DNA Polymerase α in Murine Cells

Abstract

In prokaryotes as well as in eukaryotes, extensive analysis of purified replicating DNA has shown that the Okazaki fragments are initiated by RNA primers (1). They are oligoribonucleotides, approximately 10 nucleotides in length, which are covalently attached to 5’-termini of newly synthesized DNA. They are not synthesized by any RNA polymerase involved in transcription but by another enzyme called primase. Such a primase has been described in eukaryotic cells by several authors (2–10). The primase purified from mouse hybridoma cells (10) was found to be very easily separable from DNA polymerase a, and the most highly purified fraction contained two major protein components of 56, 000 and 46, 000 daltons. In most cases however, the primase appeared to remain closely associated with DNA polymerase a (2–9) throughout all the steps in purification of the holoenzyme (3–9).