Alpha and beta tubulin folding intermediates are formed through ATP-dependent interaction with TriC/CCT. In order to form a functional heterodimer, these folding intermediates undergo a series of interactions with five proteins: (cofactors A-E) following release from TriC/CCT (reviewed in Cowan and Lewis et al., 2001). These interactions are described in the reactions below. Ultimately, alpha tubulin, when associated with cofactor E, interacts with cofactor D-bound beta-tubulin. The entry of cofactor C into this complex results in the discharge of native heterodimer triggered by GTP hydrolysis in beta tubulin (Tian et al., 1997).