Mouse Anti Saccharomyces cerevisiae ribosomal protein L3 Hybridoma, clone 8.2.2 [TdSQM4]

We have isolated and characterized genomic and cDNA recombinant plasmids that encode the Dictyostelium discoideum (Dd) ribosomal protein L3 (rpL3), Genomic plasmids were identified using a probe derived from the Saccharomyces cerevisiae TCM1 gene, that encodes the yeast rpL3. The DdL3 gene contains two introns and encodes a protein 398 amino acids in length that shows a high degree of homology to the conserved rpL3 protein of both lower and higher eukaryotes. During development, both the pattern of accumulation of DdL3 mRNA and changes in its translational activity are identical to those observed for other r-protein mRNAs.

The ribosome has historically been considered to have no cell-specific function but rather serve in a "housekeeping" capacity. This view is being challenged by evidence showing that heterogeneity in the protein composition of the ribosome can lead to the functional specialization of the ribosome. Expression profiling of different tissues revealed that ribosomal protein large 3-like (Rpl3l) is exclusively expressed in striated muscle. In response to a hypertrophic stimulus, Rpl3l expression in skeletal muscle was significantly decreased by 82% whereas expression of the ubiquitous paralog Rpl3 was significantly increased by similar to fivefold. Based on these findings, we developed the hypothesis that Rpl3l functions as a negative regulator of muscle growth. To test this hypothesis, we used the Tet-On system to express Rpl3l in myoblasts during myotube formation. In support of our hypothesis, RPL3L expression significantly impaired myotube growth as assessed by myotube diameter (-23%) and protein content (-14%). Further analysis showed that the basis of this impairment was caused by a significant decrease in myoblast fusion as the fusion index was significantly lower (-17%) with RPL3L expression. These findings are the first evidence to support the novel concept of ribosome specialization in skeletal muscle and its role in the regulation of skeletal muscle growth. (C) 2015 Wiley Periodicals, Inc.