Jourdain L, Curmi P, Sobel A, Pantaloni D, Carlier M F
Dynamique du cytosquelette, Laboratoire d'Enzymologie et Biochimie structurales, CNRS, 91198 Gif-sur-Yvette, France.
Biochemistry. 1997 Sep 9;36(36):10817-21. doi: 10.1021/bi971491b.
Stathmin is an important regulatory protein thought to control the dynamics of microtubules through the cell cycle in a phosphorylation-dependent manner. Here we show that stathmin interacts with two molecules of dimeric alphabeta-tubulin to form a tight ternary T2S complex, sedimenting at 7.7 S. This complex appears in slow association-dissociation equilibrium in the analytical ultracentrifuge. The T2S complex is formed under a variety of ionic conditions, either from GTP- or GDP-tubulin or from the tubulin-colchicine complex. The S16/25/38/63E mutated stathmin in contrast is in rapid equilibrium with tubulin in the T2S complex. The T2S complex cannot polymerize in microtubules nor in ring oligomers. Stathmin acts as a pure tubulin-sequestering protein via formation of the T2S complex. It does not act directly on microtubule ends to promote catastrophe nor enhance microtubule dynamics.
Stathmin是一种重要的调节蛋白，被认为通过磷酸化依赖的方式在细胞周期中控制微管的动力学。我们在此表明，Stathmin与两分子的二聚体αβ-微管蛋白相互作用，形成紧密的三元T2S复合物，沉降系数为7.7 S。该复合物在分析超速离心机中以缓慢的缔合-解离平衡形式出现。T2S复合物在多种离子条件下形成，可由GTP-或GDP-微管蛋白或微管蛋白-秋水仙碱复合物形成。相比之下，S16/25/38/63E突变的Stathmin在T2S复合物中与微管蛋白处于快速平衡状态。T2S复合物不能在微管中或环状寡聚物中聚合。Stathmin通过形成T2S复合物作为一种纯粹的微管蛋白隔离蛋白。它不直接作用于微管末端以促进灾难发生，也不增强微管动力学。
