Alternative transcription start site selection leads to large differences in translation activity in yeast

Model for the role of transcription start-site selection in translational control of gene expression. (A) Turning genes on and off by switching between poorly translated and efficiently translated 5′ UTR isoforms. (B) Heterogeneous transcription start-site selection produces 5′ UTR isoforms that respond differently to global changes in translation factor activity. In this example, the “long” 5′ UTR variant is better translated than the corresponding “short” isoform under stress conditions, causing reduced cap-dependent initiation due to sequestration of eIF4E.