Molecular events in the reproduction of animal cells. I. The effect of puromycin on the duplication of DNA.

Abstract

Summary The initiation of DNA synthesis was studied in cultures of HeLa cells which were synchronized by the induction and timely reversal of a thymidineless state. It was observed that the synthesis of DNA was initiated at a slow rate but was more than doubled after 2 hours. This acceleration of DNA synthesis could be prevented with amounts of puromycin which simultaneously inhibited protein synthesis. Puromycin, however, did not inhibit DNA synthesis which was in progress at the time of addition, whereas its effects on protein synthesis were immediate. The data support the concept that the synthesis of DNA in the mammalian cell is a focalized phenomenon and that localized changes involving protein synthesis are required to initiate the replication process.