A sequence in the Drosophila H3-H4 Promoter triggers histone locus body assembly and biosynthesis of replication-coupled histone mRNAs.

Compartmentalization of RNA biosynthetic factors into nuclear bodies (NBs) is a ubiquitous feature of eukaryotic cells. How NBs initially assemble and ultimately affect gene expression remains unresolved. The histone locus body (HLB) contains factors necessary for replication-coupled histone messenger RNA transcription and processing and associates with histone gene clusters.