Highly transcribed DNA regions (green) surround mRNA-processing domains (blue).
Splicing factors and other proteins that process newly made transcripts accumulate in nuclear speckles called SC-35 domains. Shopland et al. find that these domains associate with R-bands, which are cytologically visible, gene-rich, and highly transcribed chromosome regions. Transcripts from both linked and unlinked genes were found within a given SC-35 domain. This shared usage indicates that the domains are not simply spots of RNA metabolic factors at an especially active locus, but are rather organized domains that may promote efficient transcript processing. Clustering of genes with numerous individual components of the large transcription and mRNA processing complexes probably hastens complex assembly and thus increases the efficiency of mRNA...
