Fig. 4: Actin is not required for γ-TuRC assembly but impacts on γ-TuRC geometry.
From: Modular assembly of the principal microtubule nucleator γ-TuRC
a The very N-terminus of GCP6 is crucial for actin binding. Immunoblot analysis of an actin IP experiment against His tagged, N-terminal fragments of GCP6 (GCP6N126-His8; GCP6N57-126-His8), co-expressed with FLAG-MZT1 in E. coli. Input and IP samples were probed against anti-actin, anti-His (GCP6) and anti-FLAG (MZT1) antibodies. Sections of representative immunoblots of one experiment are shown. IP experiments were performed in (n = 3) independent experiments and source data are provided as a Source Data file. b Cryo-EM reconstruction of γ-TuRC∆N56-GCP6 deficient in actin binding. Coloring as indicated. Spokes are numbered. c Structure and composition of the lumenal bridge in γ-TuRC∆N56-GCP6. Atomic model of resolved components (PDB 6X0U) superposed to the segmented density of the lumenal bridge. The structure is devoid of cryo-EM density for the two N-terminal helices of GCP6 and actin. Coloring as indicated. d Effect of actin integration on γ-TuRC geometry, as represented by vectors linking the Cα atoms in both conformations. Vectors are colored according to scale bar. Directionality of motion is represented by an arrow.
