Fig. 1. Transcripts, proteins and mutations at the Drosophila yuri locus. (A) Two promoters (proximal and distal) generate three classes of yuri transcripts. The two medium transcripts differ by the presence of an intron between exons 1b' and 1b''. Exon 4, the 5' boundary of which is not defined (Materials and Methods), is included in some long transcripts. The original P{GawB} insertion (yuri^c263) and the DNA deleted in three imprecise excisions (LE1, L5 and F64) are shown. (B) Three Yuri isoform classes arise from the three transcript classes. Structural motifs are indicated.