Chromodomain-mediated spreading on active genes

The formation of heterochromatin involves spreading of repressor proteins along large chromosomal domains. A new study reveals that the concept of spreading also holds true for establishing domains of active chromatin. More specifically, spreading of the Drosophila melanogaster male-specific lethal (MSL) activator complex, which is required for dosage compensation on the X chromosome, involves interaction between the MSL3 chromodomain and histone H3 methylated at lysine 36.