Fig. 1

Microtubule (MT) assembly and dynamic instability. Each tubulin has three characteristic domains, and α-tubulin and β-tubulin form a heterodimer in a 1:1 stoichiometry. The γ-tubulin ring complex, formed by the association of phosphorylated γ-tubulin and accessory proteins, provides a base onto which the tubulin dimers are added spirally, leading to its quick elongation via polymerization. Completely formed MTs experience ‘dynamic instability’ characterized by routine, balanced cycles of rescue (stable GTP-bound β-tubulin remains intact and hence dimers are added) and catastrophe (GTP hydrolysis of β-tubulin results in its subsequent dissociation from the MTs and renders it unstable). XMAP215, tau and doublecortin  promote MT rescue, whereas katanin and kinesin-13 promote catastrophe. Additionally, the PD model toxins rotenone and MPP⁺ also destabilize MTs and orchestrate their fateful demise via catastrophe, collapsing the MT-network-associated axonal commute of vital substances