Reconstitution of rat liver 60S ribosomal subunits following disassembly by dimethylmaleic anhydride.

Modification of 60S ribosomal subunits from rat liver with dimethylmaleic anhydride (60 mumols/ml) is accompanied by release of 35% of the protein. The acidic ribosomal proteins, as well as 9 basic proteins, are selectively liberated from the ribosomal subunits. Reconstitution of the protein-deficient particles with the corresponding split proteins is accompanied by substantial recovery of the original polyphenylalanine synthetic activity. The described reconstitution procedure can be used to investigate the roles played by the released proteins and the functional similarities of proteins from different sources. Hybrid reconstitution of residual ribosomal particles from rat liver or yeast with the corresponding heterologous split proteins produces subunits which have incorporated heterologous proteins but are inactive in polyphenylalanine synthesis.