Zhu X, Ding L, Pei G
Shanghai Research Center of Life Sciences, China.
J Cell Biochem. 1997 Sep 15;66(4):441-9.
Mitosin is a nuclear protein of 3,113 amino acids which has been shown to associate with the mitotic apparatus, especially the kinetochore, during mitosis. In this paper we further confirmed its association with the spindle poles in normal monkey kidney CV1 cells by indirect immunofluorescence microscopy. When the carboxyl portion of mitosin containing amino acids 2,094-3,113 (named mitosin-pTN) was stably expressed in rat fibroblast Rat2 cells using a tetracycline-inducible system, strong spindle pole association was observed in addition to expected centromere localization. The same results were achieved in Chinese hamster ovary (CHO) cells. On the other hand, mitosin-pTC containing amino acids 2,756-3,113 was not targeted to spindle poles. Use of the FLAG epitope [Hopp et al., 1988] genetically fused to each amino terminus of these mutants eliminated possible artifacts due to antibody cross-reaction, since the spindle pole localization of wild-type mitosin was confirmed with a FLAG-tagged mutant by an antibody (anti-FLAG M2 monoclonal antibody) irrelevant to antibodies to mitosin. Our data also suggested a possible interaction of mitosin with the spindle microtubules. Interaction of mitosin with the major parts of the mitotic apparatus further implies an important role in mitosis.
有丝分裂素是一种由3113个氨基酸组成的核蛋白，已证明在有丝分裂期间它与有丝分裂装置相关联，尤其是与动粒相关。在本文中，我们通过间接免疫荧光显微镜进一步证实了它在正常猴肾CV1细胞中与纺锤体极的关联。当使用四环素诱导系统在大鼠成纤维细胞Rat2细胞中稳定表达含2094 - 3113位氨基酸的有丝分裂素羧基部分（命名为有丝分裂素-pTN）时，除了预期的着丝粒定位外，还观察到了强烈的纺锤体极关联。在中国仓鼠卵巢（CHO）细胞中也得到了相同的结果。另一方面，含2756 - 3113位氨基酸的有丝分裂素-pTC并未定位于纺锤体极。将FLAG表位[霍普等人，1988年]基因融合到这些突变体的每个氨基末端，消除了由于抗体交叉反应可能产生的假象，因为野生型有丝分裂素的纺锤体极定位通过一种与有丝分裂素抗体无关的抗体（抗FLAG M2单克隆抗体）对一个FLAG标签突变体得以证实。我们的数据还表明有丝分裂素与纺锤体微管之间可能存在相互作用。有丝分裂素与有丝分裂装置主要部分的相互作用进一步暗示了其在有丝分裂中的重要作用。
