Stearns M E, Brown D L
Proc Natl Acad Sci U S A. 1979 Nov;76(11):5745-9. doi: 10.1073/pnas.76.11.5745.
Cytoplasmic tubulin and the microtubule organizing centers (MTOCs) for the cytoskeletal microtubule system of the flagellate Polytomella have been isolated. The isolated MTOCs serve as sites for the in vitro assembly of the purified tubulin protein. The major proteins (four polypeptides of molecular weights 190,000-210,000) functioning in this assembly have been extracted from the MTOCs and purified. Kinetic studies and experiments with in vivo 35S-labeled MTOC proteins (or 35S-labeled tubulin) demonstrate that these proteins function specifically in microtubule initiation and do not contribute to microtubule elongation. The results indicate that microtubule assembly in vivo is controlled by microtubule initiating proteins associated with the organelles termed MTOCs.
已分离出鞭毛虫多孢藻细胞骨架微管系统的细胞质微管蛋白和微管组织中心（MTOC）。分离出的MTOC作为纯化微管蛋白体外组装的位点。在该组装过程中起作用的主要蛋白质（四种分子量为190,000 - 210,000的多肽）已从MTOC中提取并纯化。动力学研究以及对体内35S标记的MTOC蛋白（或35S标记的微管蛋白）的实验表明，这些蛋白质在微管起始中具有特定功能，对微管延长没有作用。结果表明，体内微管组装受与称为MTOC的细胞器相关的微管起始蛋白控制。
