Saitoh N, Goldberg I G, Wood E R, Earnshaw W C
Department of Cell Biology and Anatomy, Johns Hopkins School of Medicine, Baltimore, Maryland 21205.
J Cell Biol. 1994 Oct;127(2):303-18. doi: 10.1083/jcb.127.2.303.
Here, we describe the cloning and characterization of ScII, the second most abundant protein after topoisomerase II, of the chromosome scaffold fraction to be identified. ScII is structurally related to a protein, Smc1p, previously found to be required for accurate chromosome segregation in Saccharomyces cerevisiae. ScII and the other members of the emerging family of SMC1-like proteins are likely to be novel ATPases, with NTP-binding A and B sites separated by two lengthy regions predicted to form an alpha-helical coiled-coil. Analysis of the ScII B site predicted that ScII might use ATP by a mechanism similar to the bacterial recN DNA repair and recombination enzyme. ScII is a mitosis-specific scaffold protein that colocalizes with topoisomerase II in mitotic chromosomes. However, ScII appears not to be associated with the interphase nuclear matrix. ScII might thus play a role in mitotic processes such as chromosome condensation or sister chromatid disjunction, both of which have been previously shown to involve topoisomerase II.
在此，我们描述了ScII的克隆与特性，ScII是已鉴定出的染色体支架组分中仅次于拓扑异构酶II的第二丰富的蛋白质。ScII在结构上与一种名为Smc1p的蛋白质相关，之前发现该蛋白质对于酿酒酵母中准确的染色体分离是必需的。ScII以及新出现的类Smc1蛋白质家族的其他成员可能是新型ATP酶，其NTP结合A和B位点被预计形成α螺旋卷曲螺旋的两个长区域隔开。对ScII B位点的分析预测，ScII可能通过类似于细菌recN DNA修复和重组酶的机制利用ATP。ScII是一种有丝分裂特异性支架蛋白，在有丝分裂染色体中与拓扑异构酶II共定位。然而，ScII似乎不与间期核基质相关。因此，ScII可能在有丝分裂过程中发挥作用，如染色体凝聚或姐妹染色单体分离，这两者之前都已表明涉及拓扑异构酶II。
