Polycomb epigenetic mechanisms: methylation of DNA

Published on October 1, 2007 Updated on December 31, 2017   29 min

Other Talks in the Series: Epigenetics

0:00
Hello. My name is Vincenzo Pirrotta, and this is part two of our talk about Polycomb Epigenetic Mechanisms.
0:09
As we have seen, a more useful way to look at polycomb group activities, is to think of them as involved in dynamic processes. And in particular, a polycomb complex like PRC2. PRC2 target all chromatin, not just polycomb group target sites, where it is found stably bound.
0:30
PRC2 in fact has clearly untargeted functions. If we look at histone H3 methylation at lysine 27 in the whole genome. It is clear that most of the activity of PRC2 is not to trimethylate but to dimethylate lysine 27 of histone H3. It appears that PRC2 acts on most of the nucleosomes in the genome. There is only a small percentage of histone H3 that remains unmethylated and note that a small amount at any one time is acetylated at lysine 27 and therefore cannot be methylated at that position.
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Polycomb epigenetic mechanisms: methylation of DNA

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