Seminars

Extensive work in many labs has generated a detailed picture of how transcription factors that bind to sequences in the promoter of a gene control the assembly and activity of the transcription machinery, thereby generating an appropriate amount of mRNA. It is therefore especially surprising to find that some introns strongly affect gene expression in a way that does not fit in with what we know about gene regulation. Much of the research on introns, including mine, has been done in plants but introns have been found to boost expression in many different organisms. I will argue that for some genes, the main DNA sequences that control transcription are found not in the promoter but in introns located up to several hundred nucleotides downstream of where transcription starts. The genes in which these introns are found are among the most highly expressed in the genome. These introns may be a previously unrecognized kind of regulatory element that generates strong constitutive gene expression, and as such have many practical uses.