Electrophoretical and immunological comparison of the ribosomal proteins of the fungus Podospora anserina and the yeast Saccharomyces cerevisiae

Immunological homologies between yeast ribosomal protein L2 and rat liver ribosomal proteins L4 and L24

Polyclonal antibodies raised against ribosomal protein (r-protein) L2 of Schizosaccharomyces pombe were used to check for cross-reactions with total r-proteins of rat liver. Using this procedure, the rat liver r-proteins, L4 and L24, were identified as being immunologically related to yeast L2. In additional, homologies between rat liver L4 and L24 were detected. The possible implications for the regulation of r-protein synthesis are discussed.

Cytoplasmic ribosomal proteins from Chlamydomonas reinhardtii: characterization and immunological comparisons

Experiments were undertaken to characterize the cytoplasmic ribosomal proteins (r-proteins) in Chlamydomonas reinhardtii and to compare immunologically several cytoplasmic r-proteins with those of chloroplast ribosomes of this alga, Escherichia coli, and yeast. The large and small subunits of the C. reinhardtii cytoplasmic ribosomes were shown to contain, respectively, 48 and 45 r-proteins, with apparent molecular weights of 12,000-59,000. No cross-reactivity was seen between antisera made against cytoplasmic r-proteins of Chlamydomonas and chloroplast r-proteins, except in one case where an antiserum made against a large subunit r-protein cross-reacted with an r-protein of the small subunit of the chloroplast ribosome. Antisera made against one out of five small subunit r-proteins and three large subunit r-proteins recognized r-proteins from the yeast large subunit. Each of the yeast r-proteins has been previously identified as an rRNA binding protein. The antiserum to one large subunit r-protein cross-reacted with specific large subunit r-proteins from yeast and E. coli.

Immunological homologies between ribosomal proteins amongst lower eukaryotes

Polyclonal antibodies were raised against the purified ribosomal proteins L1 and L2, the 5S rRNA binding protein L3, all from Saccharomyces cerevisiae, and against L1 and L2 from Schizosaccharomyces pombe (numbering according to Otaka and Osawa 1981; Otaka et al. 1983, respectively). For clarity prefixes Sc and Sp have been added to the numbering of proteins derived from S. cerevisiae and S. pombe, respectively. Ribosomal proteins from these yeasts and from Kluyveromyces marxianus, Rhodotorula glutinis, the slime mold Dictyostelium discoideum and the protozoan Tetrahymena thermophila were checked for antigenic cross-reactivity by the immunoblot technique. Anti-ScL1 bound to the largest ribosomal proteins of all organisms but not with equal strength. A fast migrating protein band from R. glutinis was also reactive. Anti-ScL2 reacted strongly with L2 or analogous proteins derived exclusively from the yeasts. Anti-ScL3 cross-reacted only with one protein band from K. marxianus, whereas anti-SpL1 cross-reacted with L1 or its analogues from the other organisms, but also with proteins of lower molecular weight. In S. cerevisiae, these proteins are located exclusively on the small ribosomal subunit. L2 or analogous ribosomal proteins of all organisms were recognized by anti-SpL2 but additionally the ribosomal protein YL28 of S. cerevisiae and fast migrating proteins of T. thermophila exhibited anti-SpL2 binding.