Fig. 6. Transgene deletions demonstrate that interaction with Pbl and Pav-KLP are required for Tum cytokinetic function. Tum transgenes with a Pav-KLP-interacting domain deletion (UAS-tum^Pav, A-E) or Pbl-interacting domain deletion (UAS-tum^Pbl, F-K) were expressed in prd stripes in tum^DH15 embryos. In all panels, anti-myc antibody shows the transgene localisation in red, tubulin localisation in green and DNA in blue. (A-E) Tum^Pav protein does not localise with microtubules or rescue cytokinesis. Binucleate cells are readily detected in both expressing and non-expressing stripes of these embryos (A, asterisks) but midbody remnants are not seen. This protein is stable and abundant, but remains diffuse and cortical throughout the mitotic cycle (metaphase, B and C; telophase, D and E). (F-K) Cortex-associated microtubule bundles form in cells expressing Tum^Pbl but cytokinesis fails. Tum^Pbl protein can bind to microtubules and locates at the spindle midzone at anaphase (arrowheads, F,G,H). Rotation of panel H reveals that much of this protein is localised in discrete foci on the cortex (I). Occasional post-metaphase cells viewed along the spindle axis confirm this cortical localisation (arrowheads, J,K). Late-anaphase and telophase cells show partial bundling of microtubules (F) but rarely show evidence of incomplete furrowing. Bar, 5 µm (A-K); 3 µm (I). Grayscale images for all color channels can be viewed in supplementary material Fig. S5.