Cells don't load new CENP-A (green) until they finish mitosis.
Centromeres serve as platforms for the kinetochores that are essential for divvying up chromosomes during mitosis. CENP-A's presence at centromeres, where it replaces the standard-issue H3 histone, poses several puzzles. On page 795 Jansen et al. answer the “when” question. The researchers applied a recently developed technique called SNAP tagging, which affixes a long-lasting label to a protein. The method allowed the team to pin down CENP-A's location and measure its turnover.
The logical time for cells to begin inserting fresh CENP-A into chromosomes is after S phase, to counter the dilution of the protein during DNA duplication. But what the researchers found was one of those...
