Evolution of the multi-tubulin hypothesis

Microtubules are organized into diverse cellular structures in multicellular organisms. How is such diversity generated? Although highly conserved overall, variable regions within α- and β-tubulins show divergence from other α- and β-tubulins in the same species, but show conservation among different species. Such conservation raises the question of whether diversity in tubulin structure mediates diversity in microtubule organization. Recent studies probing the function of β-tubulin isotypes in axonemes of insects⁽¹⁾ suggest that tubulin structure, through interactions with extrinsic proteins, can direct the architecture and supramolecular organization of microtubules.