Fig. 1. Drosophila Rab6 shows a dynamic localization and is enriched on Golgi membranes. (A) Drab6 mutant oocytes rescued by GFP-Drab6 expression showed a stage-dependent distribution. Drab6 was central during stages 7 and 8 (arrow, in 40% of cases Drab6 expression was central, n=112), uniform during stage 9 (86%, n=81) and always juxtaposed to the oocyte cortex from the end of stage 9 onward (n=64). (B) RFP-Drab6 and PDI-GFP co-expressing egg chamber. (C) Colocalization of Drab6 and effects of its loss on different Golgi markers in control (I,II,IV,V,VII,VIII) and rab6^D23D (III,VI,IX) oocytes. Lva (I) colocalized with Drab6 in a rescued egg chamber mainly at the cortex (II, arrows), but global Lva localization did not depend on Drab6 (III). GalT (IV) colocalized with RFP-Drab6 in the center during stage 8 (V, arrow; inset in IV is a stage 10 egg chamber), but did not accumulate in the center in rab6^D23D (VI). WGA was central during stage 8 (VII arrow), colocalized with GalT (VIII, arrow), but formed abnormal ring-like aggregates in rab6^D23D (IX, arrow in inset, which is a magnified view of the boxed area). (D) Immunoblots of fractions from a membrane density gradient of GalT-expressing ovaries tested with markers specific to the Golgi (Dynactin), the ER (KDEL and Syntaxin 5) and the plasma membrane (Syntaxin 5). GalT was predominantly enriched in fractions containing Golgi membranes, but was additionally found in fractions reflecting the plasma membrane. Vertical bars to the left indicate the sedimentation profile: ER, endoplasmatic reticulum; PM, plasma membrane. Scale bars: 20 µm.