Gerhart J, Wu M, Cyert M, Kirschner M
Cytobios. 1985;43(174S):335-47.
When an M-phase promoting factor (MPF) is injected into Xenopus oocytes, which are naturally arrested at the G2/prophase boundary, it induces rapid entry of the cells into M-phase. MPF is present in late G2 and in M-phase of a variety of cell types, such as Xenopus eggs (naturally arrested in M), cleaving embryos, yeast, HeLa, and CHO cultures. MPF has been purified approximately 50-fold from eggs. It is stabilized by gamma-thio-ATP and by phosphoprotein phosphatase inhibitors. It runs as a protein of approximately 100 kd size on gel filtration. Oocytes contain a precursor of MPF, which is activated by post-translational means when a small amount of purified MPF is injected into the cell. Thus, MPF appears to be an auto-activating cytoplasmic trigger of M-phase. At anaphase of the cell cycle, MPF is inactivated due to the appearance of an 'anti-MPF' activity. Monoclonal antibodies have been prepared to partially purified MPF stabilized by gamma-thio-ATP, and several preparations which inactivate MPF were obtained. The antibodies are directed against thio-phosphate groups carried by a set of proteins including MPF. This indicates that MPF is present in our active preparations as a thio-phosphoprotein. These and other data suggest that MPF is normally activated in the cell cycle by a phosphorylation reaction.
当将M期促进因子（MPF）注入非洲爪蟾卵母细胞时，这些卵母细胞自然停滞在G2/前期边界，MPF会诱导细胞迅速进入M期。MPF存在于多种细胞类型的G2晚期和M期，如非洲爪蟾卵（自然停滞在M期）、正在分裂的胚胎、酵母、HeLa细胞和CHO细胞培养物中。MPF已从卵中纯化了约50倍。它可被γ-硫代ATP和磷蛋白磷酸酶抑制剂稳定。在凝胶过滤中，它表现为一种大小约为100kd的蛋白质。卵母细胞含有MPF的前体，当将少量纯化的MPF注入细胞时，该前体通过翻译后方式被激活。因此，MPF似乎是M期的一种自激活细胞质触发因子。在细胞周期的后期，由于“抗MPF”活性的出现，MPF被灭活。已经制备了针对由γ-硫代ATP稳定的部分纯化MPF的单克隆抗体，并获得了几种使MPF失活的制剂。这些抗体针对包括MPF在内的一组蛋白质所携带的硫代磷酸基团。这表明在我们的活性制剂中，MPF以硫代磷蛋白的形式存在。这些以及其他数据表明，MPF在细胞周期中通常通过磷酸化反应被激活。
