Denoya C, Costa Giomi P, Scodeller E A, Vásquez C, La Torre J L
Eur J Biochem. 1981 Apr;115(2):375-83. doi: 10.1111/j.1432-1033.1981.tb05248.x.
A processing endoribonuclease was isolated from the cytoplasm of chick embryos. The enzyme was easily obtained using an RNA extraction procedure based on a mild deproteinization with Sarkosyl and cold phenol/chloroform. This technique assured the recovery of several proteins and the endoribonuclease in association with the RNA. It was demonstrated that this endoribonuclease was capable of promoting, in vitro, a precise processing of naked 45-S ribosomal RNA precursor to molecules resembling the intermediates as well as the 28-S and 18-S cytoplasmic RNAs found in vivo. The presence of magnesium ions was required for the correct processing function of the enzyme. In addition, under the same conditions, the mature ribosomal RNA substrates were degraded at a slower rate by this RNA-associated RNase. It was possible to fractionate the enzymatic preparation into two different populations by means of a sucrose gradient: one associated and the other partially free of an RNA component. The effect of the intrinsic RNA associated with the endoribonuclease on the enzymatic activity was tested by analyzing both the enzymatic populations and the total enzymatic preparation treated with pronase or with immobilized pancreatic RNase. In all cases in which the RNA component was present, the enzyme showed processing activity. On the other hand, when the RNA component was absent or at least partially degraded the enzyme proved to be more active in processing precursor molecules and in promoting extensive degradation of mature RNA species. Although the presence of RNA in association with the enzyme was demonstrated, its role in the regulation of the enzymatic activity is yet not clear.
一种加工性内切核糖核酸酶是从鸡胚细胞质中分离出来的。使用基于用十二烷基肌氨酸钠温和脱蛋白以及冷酚/氯仿的RNA提取程序，很容易获得这种酶。该技术确保了几种蛋白质以及与RNA结合的内切核糖核酸酶的回收。结果表明，这种内切核糖核酸酶能够在体外将裸露的45 - S核糖体RNA前体精确加工成类似于体内发现的中间体以及28 - S和18 - S细胞质RNA的分子。酶的正确加工功能需要镁离子的存在。此外，在相同条件下，这种与RNA相关的核糖核酸酶降解成熟核糖体RNA底物的速度较慢。通过蔗糖梯度可以将酶制剂分成两个不同的群体：一个与RNA成分结合，另一个部分不含RNA成分。通过分析用链霉蛋白酶或固定化胰核糖核酸酶处理的两个酶群体以及总酶制剂，测试了与内切核糖核酸酶相关的内在RNA对酶活性的影响。在所有存在RNA成分的情况下，该酶都表现出加工活性。另一方面，当RNA成分不存在或至少部分降解时，该酶在加工前体分子和促进成熟RNA物种的广泛降解方面表现出更高的活性。尽管已证明酶与RNA结合存在，但其在酶活性调节中的作用尚不清楚。
