Protein composition of nuclear 14 S ribonucleoprotein particles containing poly (A)

Nuclear 14 S RNP particles containing poly (A) from Ehrlich ascites carcinoma cells and rat liver were purified by re-sedimentation in sucrose gradients, by Cs2SO4 density gradient centrifugation and by affinity chromatography on a poly (dT)-Sepharose column. Proteins of these RNP particles were electrophoresed in urea and SDS-polyacrylamide gels. RNP particles of ascites carcinoma cells contain two main bands having molecular weights of 51 000 and 69 000 daltons, respectively, and two or three minor components.