Fig. 3. Drab6 interacts with BicD in Drosophila. (A) Schematic of BicD. Exemplary truncated BicD clones containing the C-terminal H4 coiled-coil domain that interacted with Drab6 in the two-hybrid screen. (B) Interaction of Drab6 and BicD. (I) Western blot. GST-Drab6 specifically retained BicD. Preloading GST-Drab6 with the non-hydrolyzable GTP analog, GTP--S, yielded an improved interaction. In addition to BicD (89 kDa), a polypeptide of lower molecular weight (probably a degradation product, 60 kDa) was specifically retained on GST-Drab6 beads and could be revealed with the 1B11 but not the 4C2 antibody (II). (III-V) Frames taken from time-lapse recording of BicD-GFP (III) and RFP-Drab6 (IV) co-expressing egg chamber, which colocalized to several aggregates in nurse cells and the oocyte (V). (C) Drab6 accumulates in the center (arrow) in GFP-Drab6-rescued egg chambers (I). In BicD^mom egg chambers of equal age (II), GFP-Drab6 accumulation in the center was abolished (arrow). In BicD^mom oocytes, Grk protein accumulated in ring-like structures remote from the nucleus (III, arrow in inset, which is a magnification of the upper boxed area). Asterisk, position of oocyte nucleus. Scale bars: 20 µm.