Kavsan V M, Ryndich A V, Lukshina O L, Kok I P, Graevskaia N A, Samarina O P, Baĭsar D, Georgiev G P
Mol Biol (Mosk). 1975 Sep-Oct;9(5):768-74.
Template activity of nuclear pre-mRNA has been investigated in DNA-polymerase reaction. Active synthesis of DNA was demonstrated on pre-mRNA as a template in the absence of primer. A part of synthetic activity may be attributed to the traces of DNA present in the pre-mRNA preparation. Addition of oligo(dT)10 to the template stimulated the synthesis of DNA product due to transcription of heteropolymeric regions near the poly(A). The rate of DNA synthesis was different depending on the fraction of template used: the RNA extracted by hot phenol at 85 degrees showed higher template activity without adding of primer than the 65 degrees C fraction. On the contrary 65 degrees C pre-mRNA which is known to contain greater quantity of molecules with poly(A) at the 3'-end is more strongly stimulated by addition of oligo(dT). The nuclear RNA corresponding to the precursors of rRNAs extracted at 40 degrees C were not transcribed by the reverse transcriptase. The size of the DNA-product (about 7-8S in alkaline sucrose gradient) did not depend on the size of the template neither on the presence of oligo(dT)10 primer. The inhibition of the second DNA strand synthesis with actinomycin D had also no influence on the size of DNA-product.
已在DNA聚合酶反应中研究了核前体mRNA的模板活性。在没有引物的情况下，以前体mRNA为模板证明了DNA的活性合成。部分合成活性可能归因于前体mRNA制剂中存在的微量DNA。向模板中添加寡聚（dT）10由于聚（A）附近异聚区域的转录而刺激了DNA产物的合成。DNA合成速率因所用模板的组分而异：85℃下用热酚提取的RNA在不添加引物的情况下显示出比65℃组分更高的模板活性。相反，已知在3'端含有更多聚（A）分子的65℃前体mRNA在添加寡聚（dT）时受到更强的刺激。40℃下提取的与rRNA前体相对应的核RNA不会被逆转录酶转录。DNA产物的大小（在碱性蔗糖梯度中约为7-8S）既不取决于模板的大小，也不取决于寡聚（dT）10引物的存在。用放线菌素D抑制第二条DNA链的合成对DNA产物的大小也没有影响。
