Fig. 8. Model for involvement of XKLC and GBP in translocation of dorsal determinants. At the onset of cortical rotation (A), KLC bound to KHC on the subcortical microtubule array nucleates particles that include GBP and its binding partner Dsh. As cortical rotation progresses (B), kinesin transports these particles along the rapidly aligning microtubule bundles towards their plus ends, which are oriented toward the prospective dorsal marginal zone (d). Upon reaching the prospective dorsal region (C), Dsh recruits GBP to the ß-catenin degradation complex by binding to Axin (horizontal yellow oblong), which is bound to APC (vertical mauve oblong). GBP dissociates from KLC in favor of binding to GSK3, thereby removing GSK3 from the Axin complex by competing with Axin for its binding. The removal of GSK3 from the degradation complex allows ß-catenin to accumulate in the dorsal region, where it later activates the transcription of dorsal organizer genes.