The primary structure of rat ribosomal protein S12. The relationship of rat S12 to other ribosomal proteins and a correlation of the amino acid sequences of rat and yeast ribosomal proteins.

The covalent structure of the rat 40 S ribosomal subunit protein S12 was determined from the sequence of amino acids in tryptic, chymotryptic, thermolytic, and cyanogen bromide peptides and inferred from the sequence of nucleotides in a recombinant cDNA. Rat ribosomal protein S12 contains 129 amino acids and has a molecular weight of 14,120. The amino acid sequences of a number of ribosomal proteins appear to be related to rat S12. These include spinach chloroplast L7, Escherichia coli S5, Nicotiana tabacum chloroplast S18, and Bacillus stearothermophilus S12, and perhaps others. In addition, there are two sequences, 26 and 18 amino acids in length, in rat S12 that may be related to segments of the same number of residues in ribosomal proteins from a number of species. These, and other results, reinforce the suggestion that ribosomal proteins form an extended family.