Xylosylation of the Notch receptor preserves the balance between its activation by trans-Delta and inhibition by cis-ligands in Drosophila
Fig 1
Shams inhibits Notch activation in response to increased levels of Delta but not Serrate.
All wings are from females raised at 30°C. (A) Adult wing of a wild-type fly. Wing veins are numbered. The arrow marks the posterior cross-vein (PCV). (B,C) Adding two additional genomic copies of Delta (Dlgt-wt) (B) or Serrate (Sergt-wt) (C) does not affect adult wings. (D) shamsΔ34/Df mutants partially lose L4 and L5 wing veins. (E) Dlgt-wt/+ shamsΔ34/Df animals have a partial loss of L2 vein (red arrow), which is not observed in shamsΔ34/Df animals. (F) Sergt-wt/+ shamsΔ34/Df wings are indistinguishable from shamsΔ34/Df wings (compare to D). (G) Providing an additional genomic copy of Notch (Ngt-wt) induces extra wing vein material at the L2 (red asterisk) and occasionally at the L5 wing vein indicative of Confluens phenotype. (H) Ngt-wt/+; Dlgt-wt/+ animals exhibit no wing vein defects (compare to G). (I) Ngt-wt/+; Sergt-wt/+animals do not show extra vein around L2 but occasionally show extra wing vein near L5. (J) Providing an additional genomic copy of Notch lacking the functional xylosylation sites (Ngt-16_20) induces extra wing vein material near the L5 wing vein. (K) Ngt-16_20/+; Dlgt-wt/+animals exhibit a partial loss of L5 (71% penetrant, n = 17). (L) Ngt-16_20/+; Sergt-wt/+ wings are indistinguishable from Ngt-16_20 wings (n = 15) (compare to J).