FIG. 1.

The Drosophila dys gene encodes a bHLH-PAS protein. (A) The sequence structure of the Drosophila dys gene was determined by comparing the genomic sequence derived from the Celera/BDGP sequence data with cDNA sequence derived by RT-PCR of embryonic RNA. The dys gene consists of 10 exons, shown as blocks numbered 1 to 10. Filled blocks indicate coding sequence and unfilled blocks the 5′-UTR and 3′-UTR. The direction of transcription is shown by the arrow following “dysfusion.” The scale bar is shown below the schematic. The EST LP05454 is transcribed in the opposite direction (arrow) and spans 1,560 bp. The 3′ end of LP05454 overlaps exon 10 by 475 bp. (B) The conceptual protein sequence of Drosophila dys is shown with the one-letter amino acid code. The bHLH, PAS-1, and PAS-2 domains are indicated above the sequence. The extent of the domains was determined by comparison of these proteins to existing bHLH-PAS proteins by using the PAS domain definitions of Taylor and Zhulin (47). The length of the protein is 918 aa, and numbering is shown to the left of the sequence. The protein region used to generate Dys antisera spans aa 615 to 834 and is indicated above the sequence (Dys antigen). (C) The bHLH domains of Dys subfamily proteins were aligned, and the alignment shows the high degree of identity between D. melanogaster Dys (D-Dys), A. gambiae Dys (An-Dys), C. elegans C15C8.2 (Ce-C15C8.2), and H-NXF. Identities are indicated by a symbol (•), and nonidentities are indicated by the appropriate amino acid residue. The residue numbering is shown to the left of each sequence.