Tubulin is a major cytoskeleton component that has three distinct forms, designated ?, ? and ? Tubulin. ? and ? Tubulins form heterodimers, which multimerize to form a microtubule filament. ? Tubulin forms a soluble multiprotein particle with several other proteins. This particle, designated the gammasome, is required for nucleating microtubule filaments at the centrosome. In several organisms, numerous isoforms of the Tubulins exist that are encoded by different genes. The ? and ? isoforms undergo a variety of post-translational modifications, which may affect microtubule stability and protein interactions. High expression of class II ? Tubulin has been seen in elongating axons, indicating a role in neurite outgrowth. Tubulins may also play a role in non-neuronal cell process formation