Ribosomal proteins from goose reticulocytes are not histones

Ribosomes were isolated from goose reticulocytes after lysis with saponin in 50 mM KCl, 1.5 mM MgCl2, 1 mM Tris, pH 7.5. Maximum yields of ribosomes were obtained about 4 days after injection of the birds with Phenylhydrazine, but ribosomal proteins did not vary with the stage of recovery.Ribosomal proteins (extracted with either HCl–urea or LiCl–urea) differed generally from histones (extracted with either HCl or HCl–urea) according to amino acid composition and to electrophoretic patterns in starch gel and in Polyacrylamide gel, but a few zones of ribosomal protein appeared to coincide electrophoretically with the main histone components. Since all of the former proteins were eluted unretarded from Amberlite CG-50 in 9% guanidinium chloride, in which all histones are adsorbed, we conclude that histones and ribosomal proteins are different classes of protein.The hazards of assuming chemical identities of proteins on the basis of limited electrophoretic evidence and the risks of misleading cross-contamination of cell fractions were demonstrated.