The events that occur between START, the point of commitment to the mitotic cell cycle, and the beginning of DNA synthesis in S phase are very poorly understood in eukaryotes. In this relatively brief period, a number of processes must take place; e.g., the enzymes required for DNA synthesis have to be produced and replisomes have to be formed and perhaps activated at the appropriate time. In addition, replication origins must be activated, and changes in DNA topology and/or chromatin structure may be necessary. Despite this complexity, genetic analysis in budding yeast has revealed few mutants that act in this part of the cell cycle. CDC7 encodes a serine/threonine protein kinase that acts very close to the start of DNA synthesis (for review, see Newlon 1988). DBF2 also encodes a protein kinase that is expressed under cell cycle control near START and causes a delay in DNA synthesis under restrictive...
No takes yet. Share an insight, caveat, or question.
Johnston et al. (1991) studied this question.