Figure 1.

Schematic representation of the su(f) gene and comparison of Su(f) proteins from D. melanogaster (mel) and D. virilis (vir). (A) The su(f) locus is depicted. Shaded boxes are coding sequences, open boxes are noncoding sequences, and the solid box is the part of intron 4 that is incorporated in the 1.3-kb RNA. The model for su(f) autoregulation proposes that the 84-kDa Su(f) protein, encoded by the full-length su(f) transcripts, stimulates utilization of the poly(A) site in intron 4, leading to formation of a truncated transcript. (B) Comparison of Su(f) proteins from D. melanogaster and D. virilis. Vertical lines indicate identical residues, colons represent similarities, and single dots represent less similar amino acids. Open boxes are tetratricopeptide-like repeats, the darkly shaded box indicates the nuclear localization signal, and the lightly shaded box is the proline-rich domain.