Purification and characterization of two ribosomal proteins of Saccharomyces cerevisiae

Abstract

Two non-acidic proteins, extracted from the ribosomes of S. cerevisiae using 1 M ammonium chloride in the presence of 50% ethanol, were purified. Similar proteins were present in other eukaryotic ribosomes tested, as determined by 2-dimensional gel electrophoresis and cross-reaction with antisera. One of the 2 yeast proteins, protein YL23, was well preserved during evolution, since antisera specific for YL23 cross-react with protein ECL11 from Escherichia coli. The structural similarity between these 2 proteins parallels a functional equivalence shown by the ability of the bacterial protein to reconstitute the activity of protein-deficient core particles from yeast. However, in contrast to protein EC L11, protein YL23 interacts with the yeast acidic proteins, forming a complex probably similar to the one made by bacterial protein EC L10 with proteins ECL7 and ECL12 in the E. coli ribosome. Protein YL23 might play similar roles to those of proteins ECL10 and ECL11 in bacteria.