Cell 135, 649–661 (2008)

A whole-genome scan of the mouse has revealed where to find the protein H2AZ, which influences gene expression. It's attached to the 'on/off switches' of genes that are important in embryonic development and tends to accompany the 'polycomb group' protein Suz12, which does a similar job.

Laurie Boyer of the Massachusetts Institute of Technology in Cambridge and her co-workers report that H2AZ can be found at 8% of these switches, or promoter regions, of protein-coding genes in embryonic stem cells. Their gene-silencing experiments showed that H2AZ is needed for embryonic stem cells to become specialized; specifically, the protein must be redistributed around the genome before the cells can acquire a fate.