Saitoh N, Goldberg I, Earnshaw W C
Department of Cell Biology and Anatomy, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Bioessays. 1995 Sep;17(9):759-66. doi: 10.1002/bies.950170905.
The mechanism of chromosome condensation is one of the classic mysteries of mitosis. A number of years ago, it was suggested that nonhistone proteins of the chromosome scaffold fraction might help chromosomes to condense, possibly by constructing a framework for the condensed structure. Recent results have shown that topoisomerase II and the SMC proteins, two abundant members of the scaffold fraction, are required for chromosome condensation and segregation during mitosis. Topoisomerase II is a well-characterized enzyme. In contrast, nothing is yet known about the function of the SMC proteins. We summarize evidence suggesting that these proteins may be enzymes whose activity is somehow involved in the establishment and maintenance of mitotic chromosome morphology.
染色体凝聚的机制是有丝分裂的经典谜团之一。若干年前，有人提出染色体支架部分的非组蛋白可能有助于染色体凝聚，可能是通过构建凝聚结构的框架来实现。最近的研究结果表明，拓扑异构酶II和SMC蛋白这两种支架部分的丰富成员，是有丝分裂过程中染色体凝聚和分离所必需的。拓扑异构酶II是一种特性明确的酶。相比之下，关于SMC蛋白的功能目前还一无所知。我们总结了相关证据，表明这些蛋白可能是酶，其活性以某种方式参与有丝分裂染色体形态的建立和维持。
