Cracking the 9+2 Code of Motile Cilia

The axoneme of motile cilia is the largest macromolecular machine of eukaryotic cells. In humans, impaired axoneme function causes a range of ciliopathies. In most motile cilia, the axoneme has a 9+2 architecture in which nine doublet microtubules surround a central pair of singlet microtubules. Use single-particle cryo-EM, we could visualize and build atomic models of the native repeating structure of the entire axoneme including the doublet microtubule, the radial spokes and the central apparatus. We further performed comparative structural studies of axoneme from different organisms and mammalian cell types.