Tubulin is the major constituent of microtubules. The gamma chain is found at microtubule organizing centers (MTOC) such as the spindle poles or the centrosome, suggesting that it is involved in the minus-end nucleation of microtubule assembly. TUB4 is an important spindle pole body component that organizes both cytoplasmic and nuclear microtubule arrays. Interacts with SPC72, SPC97 and SPC98. Present with 7200 molecules/cell in log phase SD medium. Belongs to the tubulin family.