Fig. 3. Secondary structure predictions for homologous portions of the 5' UTRs of WT regA mRNA and two mutant mRNAs (ATG2 and ATG2Stop). (A-C) Numbering starts at transcription start (+1; Fig. 2). Grey arrows indicate the location of ATG2; black arrows indicate the locations at which stop codons were introduced. The encircled portion indicates the triple hairpin region between positions 215 and 277 that is discussed in the text. Note the secondary structure in this region changed by mutations. The structures and free enthalpies of the whole 5' UTRs (dG in kcal/mole) were calculated by the program mfold [version 3.1, Zuker (Zuker, 2003)].