Polycomb Group Methylation

Science  01 Nov 2002:
Vol. 298, Issue 5595, pp. 919m
DOI: 10.1126/science.298.5595.919m

The covalent modification of histones, proteins that help package genomic DNA into chromatin, plays a critical role in gene expression and the segregation of chromosomes. The Polycomb (Pc) group of proteins have been implicated as chromatin-modifying proteins, and Cao et al. (p. 1039) now show that one of the two known Pc complexes, ESC-E(Z), specifically methylates histone H3 on residue lysine 27. This modification recruits the second complex, Polycomb repressive complex 1, likely through Polycomb protein itself, and shuts down gene expression.

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