Location of RNase activity in nuclear residual structures

We report here the partial isolation of an RNase activity which copurifies with the nuclear residual structure prepared from both rat liver and Herpes‐infected BHK cells. After the successive treatment of purified nuclei with DNase, low salt and high salt, the RNase activity is found both in the high salt soluble supernatant fraction and in the residual nuclear structure. Triton X‐100 treatment of this structure solubilizes the RNase activity. From this we conclude that some of the RNase activity associated with the nuclear residual structure may be located in either the phospholipidic or protein moieties that were extracted with Triton X‐100. This RNase cuts rRNA non‐randomly into characteristic degradation products. Its molecular weight, on a glycerol gradient, was determined to be 25,000. 1984 Société Française des Microscopies and Société Biologie Cellulaire de France