The human inactive X chromosome (Xi) compacts into a silent nuclear compartment, called a Barr body, that is enriched in repressive histone marks. Xi compaction is now shown to require a molecular network involving the heterochromatin protein 1–binding protein HBiX1 and SMCHD1, which interact with domains enriched for trimethylated histone H3 Lys9 (H3K9me3) and for XIST RNA and H3K27me3, respectively.
- Ryu-Suke Nozawa
- Koji Nagao
- Chikashi Obuse
