Bombik B M, Huang C H, Baserga R
Proc Natl Acad Sci U S A. 1977 Jan;74(1):69-73. doi: 10.1073/pnas.74.1.69.
Nucleoli isolated from HeLa cells are functionally active but contain large amounts of RNA and proteins (RNA/DNA ratio 1:1; protein/DNA ratio 7:1). We have isolated from the nucleolus a DNA-protein complex that has the characteristics of nucleolar chromatin (RNA/DNA ratio less than 0.05:1; protein/DNA ratio 1.7:1). This nucleolar chromatin has most of the transcriptional activity of the intact nucleolus and, as assayed by circular dichroism and dye binding, has largely preserved its structure. The isolation of a transcriptionally active, fragment of chromatin, which constitutes only a small part of the total genome and codes for only one recognizable product, offers several advantages for the study of chromatin structure and function.
从HeLa细胞中分离出的核仁具有功能活性,但含有大量的RNA和蛋白质(RNA/DNA比例为1:1;蛋白质/DNA比例为7:1)。我们从核仁中分离出一种DNA-蛋白质复合物,它具有核仁染色质的特征(RNA/DNA比例小于0.05:1;蛋白质/DNA比例为1.7:1)。这种核仁染色质具有完整核仁的大部分转录活性,并且通过圆二色性和染料结合分析表明,其结构在很大程度上得以保留。分离出一种转录活性的染色质片段,它仅占整个基因组的一小部分,且仅编码一种可识别的产物,这为研究染色质的结构和功能提供了几个优势。