Replication Checkpoints

Mechanisms involved with cellular replication include checkpoints intended to allow for repair of damaged DNA prior to cell division. This of course limits the possibility that daughter cells will suffer from the effects of prior deleterious mutations. The function of one checkpoint, identified as S-phase, is associated with a protein known as HCLK2 as well as others such as ATR, ATRIP, claspin and Chk1. The checkpoint function itself could be viewed as irreducibly complex. A shortage of HCLK2 in cells leads to the degradation of the critical protein chk1 and a compromise of repair functions.1

In the words of the authors: "We conclude that HCLK2 promotes activation of the S-phase checkpoint and downstream repair responses by preventing unscheduled Chk1 degradation by the proteasome."2


1. HCLK2 is essential for the mammalian S-phase checkpoint and impacts on Chk1 stability; Nature Cell Biology - 9, 391 - 401 (2007); Spencer J. Collis, Louise J. Barber, Allison J. Clark, Julie S. Martin, Jordan D. Ward & Simon J. Boulton

2. Ibid