| Abstract: | Electrophoresis of the 60-S ribosomal subunits from rat liver in the presence of citrate ions removes the 7 S ribonucleoprotein complex between protein L5 and 5 S RNA though this complex is not released by dialysis or by centrifugation through a sucrose cushion in the same buffer. Using acetate instead of citrate, the subunits remain intact in all cases. On the other hand, in the presence of EDTA, the complex is always released. The poly(U) directed polyphenylalanine synthesis is correlated in each case with the presence of this complex within the subunits. The melting curves of subunits which have been treated with citrate, acetate or EDTA and then taken back in the buffer in which they were stored suggest that the specific RNA-protein interactions are preserved in the presence of acetate and of citrate but not of EDTA. As a whole, the results support the interpretation that the association of protein L5 and 5 S RNA exists within the active subunits. |
