NCIt definition : Microtubules of the eukaryotic cytoskeleton perform essential and diverse functions
and are composed of a heterodimer of alpha and beta tubulin. The genes encoding these
microtubule constituents are part of the tubulin superfamily, which is composed of
six distinct families. Genes from the alpha, beta and gamma tubulin families are found
in all eukaryotes. The alpha and beta tubulins represent the major components of microtubules,
while gamma tubulin plays a critical role in the nucleation of microtubule assembly.
There are multiple alpha and beta tubulin genes and they are highly conserved among
and between species. (from LocusLink);