<cell biology, protein> Abundant cytoplasmic protein (55 kD), found mainly in two forms, _ and _. A tubulin heterodimer (one _, one _), constitutes the protomer for microtubule assembly. Multiple copies of tubulin genes are present (and are expressed) in most eukaryotic cells studied so far. The different tubulin isoforms seem, however, to be functionally equivalent. _ _ tubulin is localised in centrosome and is involved in nucleation of microtubule assembly during the cell cycle. Highly conserved from yeast to mammals.

This entry appears with permission from the Dictionary of Cell and Molecular Biology

(11 Mar 2008)