Protein-Synthetic Activity of a Rat Liver Microsomal Fraction that Sediments at 600g

Similar differences were also found to exist in the ribonuclease hydrolysis of the two subunits of bacterial ribosomes (Godson & Cox, 1970). The different response of the subunits to hydrolysis by ribonuclease may indicate differences in the structural organization of the subunits. The electrophoretic pattern of RNA obtained from ribonuclease-treated subunits is shown in Fig. 2. The results indicate that the peak that appeared at the 18 S position in the gradient (Fig. Ih) after ribonuclease treatment (0.8ng/E260 unit) of the larger subunit consists of three main bands, and other minor bands migrating between 28 S and 18 S RNA can also be detected on the electrophoretogram (Figs. 2b and 2c). The fact that when the amount of ribonuclease is increased from 0.6 to 1.4ng/E2ao unit no further electrophoretic bands appear, but the intensity of already existing bands increases, may mean that there are few preferentially accessible regions on the surface of the larger subunit. These features of degradation may be exploited to yield specific RNA and ribonucleoprotein fragments that are useful in further studies.