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 libr aries constructed in bacteriophage lambda and in a cosmid vector. One of the cosmid clones isolated, cos1.1, contains the whole L7a gene, co mposed of eight exons and seven introns spanning 3226 bp. As in other mammalian housekeeping genes, the promoter and the first exon of the L 7a gene reside within a CpG-rich island. Furthermore, similar to the o ther higher eukaryote r-protein-encoding genes characterized so far, t he human L7a gene has a C as the major transcriptional start point loc alized in a pyrimidine-rich region and lacks a canonical TATA sequence . We show that 130 bp of the human L7a gene 5'-flanking region represe nt the minimal element required to promote its transcription. This ele ment is strikingly conserved between the mouse and human L7a genes. Fi nally, a comparison of the human L7a gene coding sequence and the pred icted amino acid (aa) sequence with the sequences of mouse L7a, rat L7 a, and the homologous yeast L4 shows that the aa sequence has been hig hly conserved during evolution.