HUMAN L7A RIBOSOMAL-PROTEIN - SEQUENCE, STRUCTURAL ORGANIZATION, AND EXPRESSION OF A FUNCTIONAL GENE

A cDNA coding for the human L7a ribosomal protein (r-protein) was used to isolate the corresponding gene by screening two human genomic libraries constructed in bacteriophage lambda and in a cosmid vector. One of the cosmid clones isolated, cos1.1, contains the whole L7a gene, composed of eight exons and seven introns spanning 3226 bp. As in other mammalian housekeeping genes, the promoter and the first exon of the L7a gene reside within a CpG-rich island. Furthermore, similar to the other higher eukaryote r-protein-encoding genes characterized so far, the human L7a gene has a C as the major transcriptional start point localized in a pyrimidine-rich region and lacks a canonical TATA sequence. We show that 130 bp of the human L7a gene 5'-flanking region represent the minimal element required to promote its transcription. This element is strikingly conserved between the mouse and human L7a genes. Finally, a comparison of the human L7a gene coding sequence and the predicted amino acid (aa) sequence with the sequences of mouse L7a, rat L7a, and the homologous yeast L4 shows that the aa sequence has been highly conserved during evolution.