Purification of nuclear ribonucleoprotein complexes containing poly(adenylic acid)

Nuclear 14 S ribonucleoprotein particles containing poly(adenylic acid) were isolated from Ehrlich ascites carcinoma cells and purified by a two step method. The nuclear extract obtained at an ionic strength of 0.1 was treated by pancreatic and T1 ribonucleases and sedimented in a 15-30% sucrose gradient. The 14 S peak containing 50-60% poly(adenylic acid) was chromatographed on a poly(dT)-Sepharose column. The particles thus obtained were of high purity: they had an adenosine content of 90% and a protein moiety characteristic of the 14 S nuclear particles i.e. polypeptides with molecular weight of 51 000, 61 000 and 69 000 daltons.