Fig. 1. The Drosophila Dystroglycan gene and protein. (A) Schematic drawing of the Dystroglycan genomic region, deletion alleles and the dsDG RNAi construct. The scale bar refers to P1 clone DS03910. (B) Comparison of DG from human, Drosophila (D.m DG) and C. elegans (C.e, T21B6.1). Through Psi Blast search with D.m DG protein sequence, the following E values were obtained after the third reiteration: human DG, e^-134; C.e, T21B6.1, e^-112. The dark-green box indicates the region of highest amino acid identity (human DG to D.m DG, 31%; D.m DG to T21B6.1, 20%). The light-green box indicates a duplicated region in D.m DG with 25% amino acid identity to amino acids 492-733 of human DG (broken green line). Blue box, mucin-like domain; gray box, putative transmembrane domain. (C) The last 13 amino acids of the DG C terminus, including the Dystrophin-binding site, are highly conserved between human, mouse and Drosophila. (D) Alignment of the cytoplasmic domains of human DG, mouse DG, Drosophila DG and C.e hypothetical protein T21B6.1 with ClustalW program at EBI. (E) Western blot of 6-20 hour embryonic protein extracts probed with the DG antibody. Five bands at molecular weight of 79, 105, 120, 200 and >200 kDa are detected in wild-type (OrR, lane 4, marked by red dots) and the heterozygous mutant (lanes 5-7) embryos, respectively. All five bands are missing in homozygous deficiency (Df (2R)JP4 and Df(2R)JP6) embryos (lanes 1 and 2). However, this antibody detects a background band at 110 kDa. In the homozygous Dg²⁴⁸ embryos (lane 3), only a remnant of the 105 kDa band is detected in addition to the background band. A similar banding pattern is observed in Dg³²³ embryos (data not shown). An antibody against -Tubulin was used as a loading control, while an antibody against ß-Galatosidase was used as a control to examine the purity of the homozygous mutant embryos. (F) A stage 4-5 egg chamber with Dg³²³ follicle cell clones marked by lack of GFP (green). DG staining (red) is strongly reduced in the clone (broken line, arrow). (G) DG staining (red) is strongly reduced in follicle cells carrying tubP-Gal4/dsDG to target-silence DG expression by RNAi. Blue, DAPI staining in the nuclei.

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