{c}

<SAS-6> is a family of scaffold <proteins> required for normal <centriole> assembly. Elongated <SAS-6> dimers can associate through their head domains to form the central hub and radiating spokes of the <centriole> cartwheel. This supplies a molecular route from interactions between <proteins> to the ninefold organization of a much larger <organelle>.

<Daiju Kitagawa> and colleagues combined <protein structure> determination, assembly experiments and cellular perturbations. Their model arranged nine dimers into a ring; <electron microscopy> of recombinant algal <SAS-6> showed cartwheel-like assemblies, while mutations that impaired head-domain association also impaired <centriole> formation. The isolated structure alone would show a possible geometry; its agreement with assembly and perturbation experiments connects that geometry to function.<Structural basis of the 9-fold symmetry of centrioles by Daiju Kitagawa and others>[2011, summary and Figures 2, 5–6: head interface, nine-dimer model and recombinant Bld12p assemblies]{ref}


 SAS-6 (source code)