Tubulin binding, enzymatic activity, and overall T2R–TTL structure. (A) Enzyme activity tests (bars) and T2R-binding properties (symbols on top of the bars) of wild-type (WT) and different mutants of TTL. Error bars indicate SEM. The T2R-binding properties were assessed by size exclusion chromatography (see Fig. S1 A for representative data). The binding strength of TTL variants are classified from weak binding (one cross) to strong binding (four crosses). Minus sign, no binding; n.d., not determined. (B) Overall view of the T2R–TTL complex structure in ribbon representation. α-Tubulin, β-tubulin, TTL, and the stathmin-like domain of RB3 are shown in light gray, dark gray, blue, and green, respectively. The C-terminal tail region of α1-tubulin that is bound to TTL is highlighted in orange.
