Fig. 4

Schematic representations of the uORFs in the 5′UTRs of GCN4 and FPS1 transcripts. Dark grey, numbered blocks represent uORFs in the 5´UTRs of both transcripts; dotted blocks represent the primary ORFs. a The unique 5´UTR of GCN4 contains four uORFs that prevent translation of the GCN4 ORF when levels of TC are high under normal conditions. As a result, the scanning 40S does not reach the GCN4 ORF, instead translating the uORFs [24]. b The 5′UTR of FPS1 defined by the vector pYX222-FPS1-HA₃ contains two uORFs; the effects of these uORFs were studied by generating pYX222-5′∆1-43-FPS1-HA₃ and pYX222-5′∆1-215-FPS1-HA₃, which contain only the native uORF (uORF2) or no uORFs, respectively