John P C
Plant Cell Biology Group, Research School of Biological Sciences, Australian National University, Canberra, Australia.
Prog Cell Cycle Res. 1996;2:59-72. doi: 10.1007/978-1-4615-5873-6_6.
Somatic plant cells can use a hormone checkpoint in late G2 phase. Here cytokinin stimulates removal of phosphotyrosine from p34cdc2 kinase and concurrently capacity for activation of the kinase by Cdc25 phosphatase declines while activity of the kinase increases and cells enter mitosis. Processes unique to plant mitosis are driven by the mitotically active kinase since the enzyme taken from plant cells in metaphase, when injected, can disassemble the preprophase band microtubules that form in G2 phase at the site of the future cross wall. This action is specific, since microtubules are not depolymerised when in interphase cytoplasmic array, or spindle, or phragmoplast. Plant metaphase kinase acts as MPF by accelerating chromosome condensation and nuclear envelope breakdown.
植物体细胞可在G2期后期利用激素检查点。在此过程中，细胞分裂素刺激从p34cdc2激酶上去除磷酸酪氨酸，同时Cdc25磷酸酶激活该激酶的能力下降，而激酶活性增加，细胞进入有丝分裂。植物有丝分裂特有的过程由有丝分裂活跃的激酶驱动，因为从中期植物细胞中提取的这种酶在注射后，可以分解在G2期未来横壁部位形成的前期带微管。这种作用是特异性的，因为在间期细胞质阵列、纺锤体或成膜体中的微管不会解聚。植物中期激酶通过加速染色体凝聚和核膜破裂发挥成熟促进因子（MPF）的作用。
