Numerous studies have demonstrated extensive coupling among different steps in eukaryotic gene expression, the best example being the intimate connection between transcription and RNA processing. More recently, new connections between nuclear and cytoplasmic steps in post-transcriptional gene expression have been established. The central illustration depicts the central dogma of eukaryotic gene expression and highlights the basic steps composing post-transcriptional regulation.
In the nucleus, the C-terminal domain (CTD) of the RNA polymerase II (Pol II) large subunit coordinates many RNA processing events by providing a platform for factors involved in different steps of RNA processing (reviewed by Maniatis and Reed, 2002). Splicing of pre-mRNAs can occur co-transcriptionally (for a review, see Neugebauer, 2002; Beyer and Osheim, 1988), and splicing factors that are enriched in interchromatin granule clusters (IGCs) are recruited to the sites of active transcription (Misteli et al., 1997; Lamond and Spector, 2003). Components...
