Anti β-Tubulin (C-Terminus)

A Tubulin is one of several members of a small family of globular proteins. The most common members of the tubulin family are α-tubulin and β-tubulin, the proteins which make up microtubules. Each has a molecular weight of approximately 55 kiloDaltons. Microtubules are assembled from dimers of α- and β-tubulin. To form microtubules, the dimers of α- and β-tubulin bind to GTP and assemble onto the (+) ends of microtubules while in the GTP-bound state. After being incorporated into the microtubule, the bound molecule of GTP will hydrolize into GDP. Although both subunits bind GTP, only the β-subunit has GTPase activity; that is, β-tubulin can hydrolize GTP to GDP whereas α-tubulin cannot. Whether the β-tubulin member of the tubulin dimer is bound to GTP or GDP influences the stability of the dimer in the microtubule. Dimers bound to GTP tend to assemble into microtubules, while dimers bound to GDP tend to fall apart; thus, this GTP cycle is essential for the dynamic instability of the microtubule.