THE PRIMARY STRUCTURE OF RAT RIBOSOMAL PROTEIN-S9

The amino acid sequence of the rat 40S ribosomal subunit protein S9 was deduced from the sequence of nucleotides in a recombinant cDNA. Ribosomal protein S9 has 193 amino acids, the NH2-terminal methionine is removed after translation of the mRNA, and has a molecular weight of 22,360. Hybridization of the cDNA to digests of nuclear DNA suggests that there are 14 to 16 copies of the S9 gene. The mRNA for the protein is about 1,000 nucleotides in length in part because of an especially long 5' noncoding region (103 nucleotides). Rat S9 is related to ribosomal proteins from other eukaryotes, Saccharomyces cerevisiae YS11 and Dictyostelium discoideum rp 1024, and to the eubacterial, archaebacterial, and chloroplast family of S4 ribosomal proteins. We have identified the product of the Trypanosoma brucei gene U as the homolog of rat ribosomal protein S9. © 1993 Academic Press, Inc.