Cloning and sequence analysis of ribosomal protein S18 gene (RPS18) from Ailuropoda melanoleuca

Ribosomal protein S18 is a component of the 40S subunit, encoded by the RPS18 gene in eucaryotic cell, belonging to the S13P family of ribosomal proteins. To explore the structure characteristic of RPS18 gene of the Ailuropoda melanoleuca, primers we re designed based on the known nucleotide sequence of RPS18 gene to clone the cDNA and genomic sequences of RPS18 gene of A. melanoleuca by RT-PCR and PCR strategy respectively, and then the cloned cDNA and genomic sequences were sequenced and analyzed preliminarily. The results indicated that the length of cDNA fragment of the RPS18 from the giant panda is 503 bp in size, containing an open reading frame (ORF) of 459 bp, encoding 152 amino acids. The length of the genomic sequence is 5,518 bp, with six exons and five introns. The coding sequence shows a high degree of homology to those of Homo sapiens, Bos taurus, Mus musculus, Sus scrofa, Canis lupus and Rattus norvegicus; the degree of homology was 92.16 %,92.59%, 86.64%, 91.50%, 94.77% and 89.54%, respectively. While all the homologies for amino acid sequences are high up to 98.68%. Primary structure analysis revealed that the molecular weight of the putative RPS18 protein is 17.65 KD, with a theoretical pI of 11.39. Based on topology prediction, there is one Tyrosine kinase phosphorylation site, three protein kinase C phosphorylation site, two casein kinase II phosphorylation site, three amidation site and one ribosomal protein S13 signature in the RPS18 protein of the giant panda.