CDNA CLONING AND ANALYSIS OF THE GENE ENCODING RIBOSOMAL-PROTEIN L21 FROM THE TUNICATE PYURA-STOLONIFERA

cDNA of the ribosomal protein L21 gene from the tunicate, Pyura stolon ifera, has been cloned and identified by homology to the rat ribosomal protein L21 cDNA sequence. The amino acid sequences of P. stolonifera and rat, deduced from the cDNAs, are 69% identical, showing that the protein is highly conserved. In contrast to the multiple copies of rib osomal protein genes present in mammals, P. stolonifera ribosomal prot ein L21 is encoded by a single-copy gene containing little or no intro nic sequence. Furthermore, this gene is transcribed to a mRNA with a l ong 5'-untranslated leader.