ScienceDaily (Sep. 5, 2008) — Imagine having to copy an entire book by hand without missing a comma. Our cells face a similar task every time they divide. They must duplicate both their DNA and a subtle pattern of punctuation-like modifications on the DNA known as methylation. Scientists at Emory University School of Medicine have caught in action one of the tools mammalian cells use to maintain their pattern of methylation. Visualized by X-ray crystallography, the SRA domain of the protein UHRF1 appears to act like a bookmark while enzymes are copying a molecule of DNA.
