Bischoff F R, Ponstingl H
Deutsches Krebsforschungszentrum, Heidelberg, Germany.
Nature. 1991 Nov 7;354(6348):80-2. doi: 10.1038/354080a0.
The product of the gene RCC1 (regulator of chromosome condensation) in a BHK cell line is involved in the control of mitotic events. Homologous genes have been found in Xenopus, Drosophila and yeast. A human genomic DNA fragment and complementary DNA that complement a temperature-sensitive mutation of RCC1 in BHK21 cells encode a protein of relative molecular mass 45,000 (Mr 45K) which is located in the nucleus and binds to chromatin. We have recently isolated a protein from HeLa cells that strongly binds an anti-RCC1 antibody and has the same molecular mass, DNA-binding properties, and amino-acid sequence as the 205 residues already identified. HeLa cell RCC1 is complexed to a protein of Mr 25K. We have shown that this 25K protein has a sequence homologous to the translated reading frame of TC4, a cDNA found by screening a human teratocarcinoma cDNA library with oligonucleotides coding for a ras consensus sequence, and that the protein binds GDP and GTP. We have referred to this protein as the Ran protein (ras-related nuclear protein). In addition to the fraction of Ran protein complexed to RCC1, a 25-fold molar excess of the protein over RCC1 was found in the nucleoplasm of HeLa cells. Here we show that RCC1 specifically catalyses the exchange of guanine nucleotides on the Ran protein but not on the protein c-Ha-ras p21 (p21ras).
BHK细胞系中RCC1基因（染色体凝聚调节因子）的产物参与有丝分裂事件的调控。在非洲爪蟾、果蝇和酵母中发现了同源基因。一个能弥补BHK21细胞中RCC1温度敏感突变的人类基因组DNA片段及互补DNA编码一种相对分子质量为45,000（Mr 45K）的蛋白质，该蛋白质定位于细胞核并与染色质结合。我们最近从HeLa细胞中分离出一种能与抗RCC1抗体强烈结合的蛋白质，其分子量、DNA结合特性以及氨基酸序列与已鉴定的205个残基相同。HeLa细胞RCC1与一种Mr 25K的蛋白质形成复合物。我们已证明这种25K蛋白质具有与TC4翻译阅读框同源的序列，TC4是通过用编码ras共有序列的寡核苷酸筛选人类畸胎瘤cDNA文库而发现的一种cDNA，并且该蛋白质能结合GDP和GTP。我们将这种蛋白质称为Ran蛋白（ras相关核蛋白）。除了与RCC1形成复合物的那部分Ran蛋白外，在HeLa细胞核质中发现该蛋白质的摩尔量比RCC1高25倍。在此我们表明，RCC1特异性催化Ran蛋白上鸟嘌呤核苷酸的交换，但不催化c-Ha-ras p21（p21ras）蛋白上鸟嘌呤核苷酸的交换。
