The similarities of ribosomal and basic chromosomal proteins from fungi.

We have compared the physical and chemical properties of yeast and fungal ribosomal proteins with those of higher eukaryotic histones. We have found that acidic urea gel electrophoresis, sodium dodecyl sulfate gel electrophoresis or chromatography on carboxymethylcellulose columns failed to distinguish ribosomal proteins from histones. The majority of the ribosomal proteins did not adsorb to an amberlite CG-50 column in the presence of 8% guanidine hydrochloride. Histones quantitatively adsorbed to an amberlite CG-50 column in the presence of 8% guanidine hydrochloride. A small number of fungal acid-soluble nuclear proteins, which coelectrophoresed with histones, were identified in a presumed nucleolar and nuclear membrane fraction. This fraction contained large amounts of RNA and small amounts of DNA. It is suggested that contamination of yeast and fungal chromosome preparations by a small number of ribosomal proteins can occur. Furthermore, several commonly employed criteria did not distinguish contaminating ribosomal proteins from authentic histones.