Yeast ribosomal proteins. VIII. Isolation of two proteins and sequence characterization of twenty-four proteins from cytoplasmic ribosomes

Summary Two proteins, YL41 and YL43, were isolated from 80S ribosomes of Saccharomyces cerevisiae by filtration through a Sephacryl S-200 column and by chromatography on a column of carboxymethylcellulose. Their amino acid compositions are presented. Twenty-four proteins including these two proteins were subjected to sequence analyses by automated Edman degradation. Amino-terminal amino acid sequences were determined for 17 proteins, YS3, YS9, YS23, YS24, YS29, YL6, YL8, YL11, YL15, YL17, YL23, YL28, YL33, YL37, YL39, YL41, and YL43. YL41, which has a 72.7% lysine and arginine content, was found to be particular to eukaryotic ribosomes. The aminotermini of another seven proteins, YS2, YS5, YS8, YS12, YS13, YS20, and YS27, were suggested to be blocked.Comparison of the amino-terminal sequences with all other ribosomal protein sequences so far available indicates that YS9 shows sequence homology to rat liver ribosomal protein S8 (Wittmann-Liebold et al. 1979).