Quantitative microscopy and theory show that the size of Xenopus laevis egg extract spindles is controlled by a spatially-regulated autocatalytic growth mechanism driven by microtubule-stimulated microtubule nucleation.
The protein TPX2 and the protein complex augmin together recruit the microtubule nucleator γ-TuRC to a pre-existing microtubule where they initiate branching microtubule nucleation.
Biochemical and genetic approaches show that the XMAP215 homolog Stu2 directly interacts with the small gamma-tubulin complex and its recruitment factor Spc72 to instigate functions in cytoplasmic microtubule organization.
Phosphorylation of Spc110 N-terminal domain encompassing conserved motifs and its interaction with conserved GCP3 N-terminal domain regulate the oligomerization of gamma-tubulin small complexes (γ-TuSCs).
Purification of two conserved protein complexes, the γ-TuRC and Augmin, using a simple affinity technique, demonstrates that they are necessary and sufficient for the essential phenomenon of branching microtubule nucleation.
A combination of cryo-electron microscopy of TPX2 bound to microtubules and in vitro reconstitution experiments reveals a novel microtubule interaction mode that explains how TPX2 promotes microtubule nucleation and stabilization.
A three-dimensional description of the cytoskeletal arrangement, cytoplasmic flows, and cargo transport in stage 9 Drosophila oocytes accurately reproduces mRNA localizations in wild-type and mutant oocytes.