Tarasov A P, Del'vig A A
Biokhimiia. 1980 Mar;45(3):526-31.
A releasing factor (RF) of polynucleotide phosphorylase (PNPase) isolated and purified from sarcoma M-1 of the rat is a protein with molecular weight of about 8000 and the isoelectric point at 4,0--4,2. The process of PNPase release from the polyribosomes of normal rat liver does not depend on the pH of the medium within the pH range of 7,2--9,0, on temperature within the interval of 0--400 degrees and on incubation time. Inhibition of phosphorolysis by endogenous RNA from normal rat liver polyribosomes requires considerable amounts of RF--approximately 170--800 molecules of RF per molecule of poly(A)+-mRNA. The data obtained suggest that PNPase release from the polyribosomes under the action of RF is not a catalytic process and is caused by competition between RF and PNPase for the binding sites on the mRNA molecule.
从大鼠肉瘤M-1中分离纯化得到的多核苷酸磷酸化酶（PNPase）释放因子（RF）是一种分子量约为8000、等电点在4.0 - 4.2的蛋白质。正常大鼠肝脏多核糖体中PNPase的释放过程在pH值7.2 - 9.0范围内不依赖于介质的pH值，在0 - 40℃的温度区间内不依赖于温度，也不依赖于孵育时间。正常大鼠肝脏多核糖体中的内源性RNA对磷酸解的抑制需要相当数量的RF——每分子聚（A）⁺-mRNA约170 - 800个RF分子。所获得的数据表明，在RF作用下多核糖体释放PNPase不是一个催化过程，而是由RF和PNPase对mRNA分子上结合位点的竞争所导致的。
