The tubulin fraternity: alpha to eta.

Microtubules perform essential and diverse functions in eukaryotic cells. They are required for spindles during mitosis and meiosis, for axonal transport, for organelle positioning, and for cilia and flagella. gamma-tubulin is necessary to initiate the assembly of alpha-beta tubulin heterodimers into microtubule polymers. Recent genetic analyses and database searches have added four new members of the tubulin superfamily, which now includes alpha-, beta-, gamma-, delta-, epsilon-, zeta-, and eta-tubulin.