The poly(A)-containing ribonucleoproteins in the nucleus and the cytoplasm of ehrlich ascites carcinoma cells.

The sedimentation characteristics and protein composition of the polyadenylic acid-containing ribonucleoprotein (RNP) particles separated from the polysomes of Ehrlich ascites carcinoma cells by means of ribonuclease treatment were studied. The results were compared with the corresponding characteristics of the poly(A)-containing particles of the cell nucleus. The sedimentation coefficient of the poly(A)-containing RNP from poly-ribosomes was found to be 11 S, while that of the nuclear particles was 14 S. In Cs2SO4 equilibrium density gradient values of p=1.25 and 1.34 gcm-3 were obtained for the nuclear particles and the poly(A)-RNP separated from polyribosomes, respectively. The molecular weights of the proteins making up the polysomal poly(A)-particles were found to be over 40 000 daltons, i.e. 54 000, 48 000, 68 000 and 89 000 daltons for the four polypeptides present in considerable amounts. As far as electrophoretic mobility is concerned these proteins were indistinguishable from the proteins of the nuclear poly(A)-containing RNP. However, the ratio of the components in the two types of particle proved to be quite different.