A rice (Oryza sativa L.) cDNA encodes a protein sequence homologous to the eukaryotic ribosomal 5S RNA-binding protein.

A rice (Oryza sativa L.) cDNA clone coding for the cytoplasmic ribosomal protein L5, which associates with 5 S rRNA for ribosome assembly, was cloned and its nucleotide sequence was determined. The primary structure of rice L5, deduced from the nucleotide sequence, contains 294 amino acids and has intriguing features some of which are also conserved in other eucaryotic homologues. These include: four clusters of basic amino acids, one of which may serve as a nucleolar localization signal; three repeated amino acid sequences; the conservation of glycine residues. This protein was identified as the nuclear-encoded cytoplasmic ribosomal protein L5 of rice by sequence similarity to other eucaryotic ribosomal 5 S RNA-binding proteins of rat, chicken, Xenopus laevis, and Saccharomyces cerevisiae. Rice L5 shares 51 to 62% amino acid sequence identity with the homologues. A group of ribosomal proteins from archaebacteria including Methanococcus vanniellii L18 and Halobacterium cutirubrum L13, which are known to be associated with 5 S rRNA, also related to rice L5 and the other eucaryotic counterparts, suggesting an evolutionary relationship in these ribosomal 5 S RNA-binding proteins.