Klein F, Laroche T, Cardenas M E, Hofmann J F, Schweizer D, Gasser S M
Swiss Institute for Experimental Cancer Research (ISREC), Epalinges s/Lausanne.
J Cell Biol. 1992 Jun;117(5):935-48. doi: 10.1083/jcb.117.5.935.
Topoisomerase II (topoII) and RAP1 (Repressor Activator Protein 1) are two abundant nuclear proteins with proposed structural roles in the higher-order organization of chromosomes. Both proteins co-fractionate as components of nuclear scaffolds from vegetatively growing yeast cells, and both proteins are present as components of pachytene chromosome, co-fractionating with an insoluble subfraction of meiotic nuclei. Immunolocalization using antibodies specific for topoII shows staining of an axial core of the yeast meiotic chromosome, extending the length of the synaptonemal complex. RAP1, on the other hand, is located at the ends of the paired bivalent chromosomes, consistent with its ability to bind telomeric sequences in vitro. In interphase nuclei, again in contrast to anti-topoII, anti-RAP1 gives a distinctly punctate staining that is located primarily at the nuclear periphery. Approximately 16 brightly staining foci can be identified in a diploid nucleus stained with anti-RAP1 antibodies, suggesting that telomeres are grouped together, perhaps through interaction with the nuclear envelope.
拓扑异构酶II（topoII）和RAP1（阻遏激活蛋白1）是两种丰富的核蛋白，在染色体的高级组织中具有推测的结构作用。这两种蛋白在营养生长的酵母细胞中作为核支架的成分共同分级分离，并且在粗线期染色体中都作为成分存在，与减数分裂细胞核的不溶性亚分级一起分级分离。使用针对topoII的特异性抗体进行免疫定位显示酵母减数分裂染色体的轴向核心有染色，延伸了联会复合体的长度。另一方面，RAP1位于配对二价染色体的末端，这与其在体外结合端粒序列的能力一致。在间期细胞核中，与抗topoII再次形成对比的是，抗RAP1产生明显的点状染色，主要位于核周边。在用抗RAP1抗体染色的二倍体细胞核中可以识别出大约16个明亮染色的焦点，这表明端粒可能通过与核膜的相互作用聚集在一起。
