The primary structure of rat ribosomal protein S3

The amino acid sequence of rat ribosomal protein S3, which has been reported to form part of the binding site for initiation factors, was deduced from the sequence of nucleotides in a recombinant cDNA. Ribosomal protein S3 contains 243 amino acids and has a molecular weight of 26,643. Rat S3 and Xenopus laevis ribosomal protein S1 are homologous: There are 62 identities in 63 consecutive residues in the carboxyl-terminal amino acid acid sequence of rat S3 and in a partial sequence of Xenopus S1. Hybridization of rat S3 cDNA to digests of nuclear DNA suggests that there are 8-10 copies of the S3 gene. The mRNA for the protein is about 950 nucleotides in length.