Stepping stone: a cytohesin adaptor for membrane cytoskeleton restraint in the syncytial Drosophila embryo.
Bottom Line: Elevating Sstn furrow levels had no effect on the steppke phenotype, but elevating Steppke furrow levels reversed the sstn phenotype, suggesting that Steppke acts downstream of Sstn and that additional mechanisms can recruit Steppke to furrows.Finally, the coiled-coil domain of Steppke was required for Sstn binding and in addition homodimerization, and its removal disrupted Steppke furrow localization and activity in vivo.Overall we propose that Sstn acts as a cytohesin adaptor that promotes Steppke activity for localized membrane cytoskeleton restraint in the syncytial Drosophila embryo.
Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.Show MeSH
Related in: MedlinePlus
Mentions: If Sstn acts as a cytohesin adaptor, then one region of the protein would be expected to bind Step, and a separate region would be expected mediate other interactions. To test this hypothesis, we generated GFP-tagged versions of Sstn, expressed them from the same genomic site with the Gal-4-UAS system, and localized them in the early embryo during peripheral nuclear divisions and early cellularization. Full-length Sstn accumulated at two main sites within the cell compartments: to pericentrosomal regions and along the basal end of pseudocleavage and early cellularization furrows (Figure 3A; arrow at basal furrow tip). We attempted to generate antibodies against both the CC domain and the CR of Sstn, but neither detected Sstn specifically in early embryos.
Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.