Weinberg E S, Overton G C, Shutt R H, Reeder R H
Proc Natl Acad Sci U S A. 1975 Dec;72(12):4815-9. doi: 10.1073/pnas.72.12.4815.
The DNA coding for histones from Strongylocentrotus purpuratus, purified up to 100-fold with the use of Hg+2-CS2-SO4 and actinomycin-CsC1 equilibrium density gradients, has been used to study the clustering of genes coding for different histones and the size of the repeating multigene cluster. When digested with EcoRI restriction endonuclease, the histone DNA is identified in two classes of fragments with molecular weights of 1.15 X 106 and 2.8 X 106, whereas after treatment of the DNA with HindIII restriction endonuclease, histone gene sequences can be identified only in a fragment of 3.95 X 106. Treatment of the DNA with both enzymes simultaneously shows that there is a HindIII site within the smaller EcoRI fragment. Partial digests with HindIII give fragment sizes that appear to be simple multiples of a 3.95 X 106 repeat. Individual histone mRNAs all hybridize to the 3.95 X 106 fragment but only to one or the other EcoRI fragments. The evidence strongly suggests a repeating unit of 3.95 X 106 containing the genes for most, if not all, the histonrs.
利用Hg²⁺ - CS₂ - SO₄和放线菌素 - CsCl平衡密度梯度将紫球海胆的组蛋白编码DNA纯化了100倍，用于研究编码不同组蛋白的基因的聚类情况以及重复多基因簇的大小。用EcoRI限制性内切酶消化时，组蛋白DNA可在分子量分别为1.15×10⁶和2.8×10⁶的两类片段中鉴定出来，而在用HindIII限制性内切酶处理DNA后，组蛋白基因序列只能在一个3.95×10⁶的片段中鉴定出来。同时用这两种酶处理DNA表明，较小的EcoRI片段内有一个HindIII位点。用HindIII进行部分消化得到的片段大小似乎是3.95×10⁶重复序列的简单倍数。各个组蛋白mRNA都与3.95×10⁶的片段杂交，但只与其中一个EcoRI片段杂交。有力的证据表明存在一个3.95×10⁶的重复单元，其中包含了大部分（如果不是全部）组蛋白的基因。
