(a) ATTO-565 labeled MTs in BRB80. (b,c) Bundling of MTs by p80 (b) and dynein (c). Addition of p80 or dynein produced a remarkable MT-bundling effect. (d) NuMA has no effect on MT bundling. (e,f) Combination of dynein and NuMA (e) or dynein and p80 (f) had no effect on MT bundling. (g) p80 bundling effect completely abolished by the addition of NuMA. (h,i) MT-bundling effect of Δ1-56 aa and p.G33W. p80 N-terminal mutation forms Δ1-56 aa (h) and p.G33W (i) both maintain MT-bundling effect. (j,k) Effect of p.S535 L and p.L540R on MT bundling. Two C-terminal mutations of p80 form numerous tiny assemblers when they interact with MTs. (l–o) Four p80 mutation forms interact with NuMA. (p) Robust aster formations by p80, NuMA and dynein. (q–t) Four p80 mutation forms have no aster formation ability despite the addition of NuMA and dynein. (u) Anti-p80 antibody was added after aster formation as indicated in Fig. 6p, and the asters formed by p80, NuMA and cytoplasmic dynein broke completely. (v) Antibody against p80 that was mixed with p80, NuMA and cytoplasmic dynein exhibited only an MT-bundling effect. All experiments were performed in 1 mM ATP conditions. Scale bar in a-o, 20 μm, and p-v, 100 μm. (w) Summarized table on regulatory functions for wild type p80 and its mutation forms derived from microlissencephalic patients.