The β-tubulin C-terminal tail region spatiotemporally regulates microtubule dynamics in an isotype-dependent manner. The β-tubulin C-terminal tail region spatiotemporally regulates microtubule dynamics in an isotype-dependent manner. Schematic of a model summarizing findings that the β-tubulin C-terminal tails regulate microtubule growth and assembly. Compared with the ubiquitous βI-tubulin C-terminal tail, the βIII-tubulin C-terminal tail increases the propensity of microtubules to grow and depolymerize in normal growth conditions and under the influence of MCAK or microtubule-stabilizing agents. The C-terminal tail region also modulates the collective dynamics of microtubules such that the β-tubulin isotype C-terminal tails confer unique dynamic properties to microtubules. E, Energy; TXL, paclitaxel; ↑ and ↓, increased or decreased levels, respectively, for the indicated parameters. Amelia L Parker et al. LSA 2018;1:e201800059 © 2018 Parker et al.