Figure 1. Draper-I is sufficient for glial clearance of degenerating axons in the adult Drosophila CNS.

(a) Draper isoform schematic. Ovals represent extracellular EGF-like motifs. NPXY is the predicted Ced-6 binding site. Draper-I contains an ITAM (YXXI-X₁₁-YXXL), which binds Shark. Draper-II contains a unique insertion (asterisk) within the ITAM. Draper-III lacks an ITAM due to a frame shift and premature stop codon.

(b) Draper Western blot (WB) on control yw adult heads. At least two bands were detected: Draper-I (113 kD) and at least one smaller band corresponding to Draper-II (65 kD) and Draper-III (59 kD). Full-length blot is presented in Supplementary Figure 1.

(c) repo-Gal4 was used to express UAS-driven transgenes of each Draper isoform in draper^Δ5 mutants that also carried OR85e-mCD8::GFP to label maxillary palp 85e ORNs. Projected confocal Z-stacks show GFP⁺ axons (green) in the antennal lobe before and after axotomy. Confocal slices of Draper immunostaining (red) show robust glial expression of Draper transgenes.

(d) Quantification of GFP⁺ axon material in Draper rescue experiments shown in (c). Bars depict mean ± S.E.M. ***p<0.001.

(e) Draper WB on head lysates of control yw, draper^Δ5, and rescue flies to confirm expression of UAS-Draper transgenes. Blot was reprobed for tubulin. Less protein lysate was loaded in rescue lanes because GAL4/UAS drives robust expression. D0, Day 0; D3, Day 3. Full-length blots shown in Supplementary Figure 1.

Genotypes and N values in (c,d): control=w;OR85e-mCD8::GFP/+;repo-Gal4/+. (D0 N=12, D3 N=12).

draper^Δ5=w; draper^Δ5. (D0 N=20; D3 N=14).

Draper-I rescue=w;OR85e-mCD8::GFP/UAS-Draper-I;repo-Gal4,drpr^Δ5/drpr^Δ5. (D0 N=31; D3=39).

Draper-II rescue=w;OR85e-mCD8::GFP/UAS-Draper-II;repo-Gal4,drpr^Δ5/drpr^Δ5. (D0 N=16; D3 N=16).

Draper-III rescue=w;OR85e-mCD8::GFP/UAS-Draper-III;repo-Gal4,drpr^Δ5/drpr^Δ5. (D0 N=23; D3 N=26).