Hirano T, Mitchison T J
Department of Pharmacology, University of California, San Francisco 94143-0450.
Cell. 1994 Nov 4;79(3):449-58. doi: 10.1016/0092-8674(94)90254-2.
We report here a chromosomal protein that plays an essential role in mitotic chromosome condensation in Xenopus egg extracts. Two polypeptides, designated XCAP-C and XCAP-E, were found to associate with each other in the extracts, presumably forming a heterodimer. During chromosome assembly in mitotic extracts, XCAP-C/E was recruited to the chromatin and formed a discrete internal structure within assembled chromosomes. Antibody blocking experiments showed that XCAP-C function is required for both assembly and structural maintenance of mitotic chromosomes in vitro. Deduced amino acid sequences revealed that the two polypeptides share common structural motifs, consisting of an N-terminal NTP-binding domain, two central coiled-coil regions, and a C-terminal conserved domain. These motifs are highly conserved in a protein family, members of which have been identified recently in both prokaryotes and eukaryotes.
我们在此报道一种染色体蛋白，它在非洲爪蟾卵提取物的有丝分裂染色体凝聚过程中发挥着至关重要的作用。在提取物中发现了两种名为XCAP-C和XCAP-E的多肽，它们可能相互结合形成异二聚体。在有丝分裂提取物中的染色体组装过程中，XCAP-C/E被募集到染色质上，并在组装好的染色体内形成离散的内部结构。抗体阻断实验表明，XCAP-C的功能对于体外有丝分裂染色体的组装和结构维持都是必需的。推导的氨基酸序列显示，这两种多肽具有共同的结构基序，包括一个N端NTP结合结构域、两个中央卷曲螺旋区域和一个C端保守结构域。这些基序在一个蛋白质家族中高度保守，该家族的成员最近在原核生物和真核生物中均已被鉴定出来。
