The primary structure of human ribosomal protein L12.

The ribosome serves as the site of protein synthesis in all cells. Biogenesis of the mammalian ribosome is a complex process involving the coordinated expression of four ribosomal RNA molecules and approximately 75 ribosomal proteins. In order to understand the mechanisms governing ribosome biosynthesis, it is necessary to elucidate the structure and organization of its components. A cDNA clone which encodes human ribosomal protein L12 has been isolated from a cDNA library constructed using poly (A+) RNA from human dermal microvascular endothelial cells. The cDNA insert is 692 nucleotides long and consists of 68 nucleotides of 5' noncoding sequence, an open reading frame comprising 495 nucleotides, and 129 residues of the 3' untranslated region. A poly (A) stretch of 80 residues is present 20 nucleotides downstream of the polyadenylation signal, AATAAA. Nucleotide sequence comparison of the cDNA exhibits a 90% sequence homology to that of rat ribosomal protein L12 (1). The amino acid sequence deduced from the open reading frame encodes a protein of 165 amino acid residues and exhibits 99.4% sequence identity with rat ribosomal protein L12. The predicted human protein contains only one amino acid change at position 101, from Asn in rat to Ser in human. The conservation of the primary structure of ribosomal proteins across species has been documented for many other ribosomal proteins (2). Northern analysis revealed a single mRNA transcript of 800 bases. Southern blot analysis of human genomic DNA reveals multiple bands, suggesting that human ribosomal protein L12 is a member of a multigene family.