Search

The BUF/Mna (BUF) strain is a high-proteinuria line of rats, and virtually all rats develop overt proteinuria by the age of 20 weeks. Genetic analysis revealed that proteinuria susceptibility was determined principally by two autosomal recessive genes. These findings prompted us to perform genetic mapping of the genes. (BUF/Mna x WKY/NCrj) F1 x BUF/Mna backcross rats were raised and maintained for 40-60 weeks to detect proteinuria. DNAs were extracted from ears of these rats and were examined by linkage study with polymerase chain reaction (PCR) with 132 microsatellite markers. Fifty-three out of 167 rats developed proteinuria. DNAs of 51 out of these 53 rats showed homozygous BUF/BUF genotype in the D13Mgh4 and D13N1 markers located on Chromosome (Chr) 13. The D13Rat1, D13Mgh2, D13Rat13, D13Mgh3, Syt2, Ren, D13Rat25, D13Mit2, D13Mgh5, and D13N2 markers located on the chromosome also showed statistically significant linkage to the development of proteinuria, whereas the other 110 markers showed no linkage. Here we report that a proteinuria-susceptible gene, Pur1, resides on a region flanked by the loci D13Mgh3 and D13Mgh4 on Chr 13.

The cytoplasmic ribosomal proteins from a fission yeast Schizosaccharomyces pombe were analysed by two-dimensional polyacrylamide gel electrophoresis. Seventy-three protein species were identified in the 80S ribosome, and named SP-S1 to SP-S33 and SP-L1 to SP-L40 in the small and large subunits, respectively. Many of these proteins could be correlated to those of Saccharomyces cerevisiae on the basis of their electrophoretic mobilities. Eleven proteins were isolated from the 80S ribosome, and their amino acid compositions were determined. Of these, SP-S6, SP-L1, SP-L12, SP-L15, SP-L17, SP-L27, SP-L36 and SP-L40c and d were sequenced from their amino-termini. SP-S28 and SP-L2 appear to have their amino-termini blocked. These results were compared with the data available for the S. cerevisiae and rat liver ribosomal proteins. The S. cerevisiae counterparts of the eight proteins mentioned above were found to be YS4, YL1, YL10, YL14, YL35, YL40 and YL44c and d, respectively. The rat liver counterparts of SP-S6, SP-L1, SP-L27 and SP-L40c and d were the rat S6, L4, L37 and P2, respectively. Comparison of the partial sequences of these ribosomal proteins suggests that these two yeasts are relatively far apart, phylogenetically.

The rate of nucleotide substitution (k(nuc)) of 5s RNA was estimated to be (1.8 +/- 0.5) x 10(-10) per site per year by comparing the nucleotide sequences of human and Xenopus 5s RNA and using the geological time elapsed since the separation of mammals and amphibians. Similarly, k(nuc) of 5.8s rRNA was calculated to be 0.93 10(-1u) per site per year from the sequences of rat hepatoma cells and Saccbaromyces cerevisiae. For the comparison of these data with the amino acid substitution rate of known proteins, the k(nuc) values of 5s rRNA and 5.8s rRNA were converted to the rate of amino acid substitution (k(aa')). The k(aa') values in pauling units were 0.4 and 2 0.3, respectively. The average k(aa) of ribosomal proteins was also estimated to be 0.2 0.3 pauling from the N-terminal amino acid sequences of seventeen 30s ribosomal proteins of Bacillus stearothermopbilus and Eschericbia coli. Thus, the evolutionary rates of these ribosomal components studied here are similar to each other; they considerably slower than that of the known cellular proteins. Most, if not all, of the replacements in ribosomal proteins occurred between amino acids of a chemically similar nature.

Twenty proteins were isolated from the 30S ribosomal subunits of Bacillus subtilis and their amino acid compositions and amino-terminal amino acid sequences were determined. These results were compared with the data of Escherichia coli 30S ribosomal proteins and the structural correspondence of individual ribosomal proteins has been established between B. subtilis and E. coli. Post-translational modifications of amino-terminal amino acids of the ribosomal proteins which have been found in E. coli are almost absent in B. subtilis with the exception of acetylated forms of S9.

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, YLll, YLI5,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 amino-termini 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).

Streptomycin-resistant and dependent mutants were isolated from Bacillus subtilis ATCC 6633. Ribosomal proteins were analysed from six such mutants with chromatography on carboxymethyl cellulose or phosphocellulose columns. An altered specific 30s ribosomal protein, 30B, could be detected in all of these mutants. Streptomycin-independent revertants were isolated from a streptomycin-dependent strain. Some of them had an altered 30s ribosomal protein, 30A, and some others had an altered 30C protein. It was shown that from the data of partial N-terminal amino acid sequences together with amino acid compositions and mobilities on two-dimensional gel electrophoresis of these proteins that 30A, 30B, and 30C proteins were homologous with S5, S12 and S4 of E. coli 30s ribosomal proteins, respectively.