Choreographing mRNA biogenesis.

Biogenesis of eukaryotic mRNA requires several post-transcriptional processing steps that must be completed accurately before it can be exported. Several processing factors are known to associate with RNA polymerase II during elongation, thereby positioning them to mediate efficient RNA processing. mRNAs are exported as complexes containing several RNA-binding proteins and other proteins. A recent study indicates that some of these packaging proteins also associate with RNA polymerase II during transcription. This suggests close coordination and mechanistic coupling of the events required to produce and export functional mRNAs.