Sobczak-Thepot J, Harper F, Florentin Y, Zindy F, Brechot C, Puvion E
INSERM U370, Faculte Necker, Paris, France.
Exp Cell Res. 1993 May;206(1):43-8. doi: 10.1006/excr.1993.1118.
Cyclin A is a nuclear protein which is part of a kinase complex with either p34cdc2 or p33cdk2. Cyclin A is required in higher eukaryotic cells at the G1/S and the G2/M transitions. To examine the relationship between cyclin A and DNA replication, we simultaneously labeled exponentially growing HeLa cells for the distribution of cyclin A and proliferating cell nuclear antigen (PCNA). We have now demonstrated, by means of immunoelectron microscopy, that cyclin A is located at the sites of DNA replication visualized by both BrdU and PCNA labeling. Thus cyclin A may play a significant role in the phosphorylation of proteins at or near the sites of DNA replication.
