Cloning of cDNA encoding a conserved RNA-binding motif from mouse brain

Abstract

A cDNA coding a novel RNA binding protein (named MRBP-b : Mouse RNA binding protein-brain) was isolated from mouse brain cDNA library. The partial sequence of MRBP exhibited a significantly high homology with previously known RNP-motif RNA binding proteins. Particulary, it showed very strong homology (over 50 % identities and 90 % positives) with drorox2 and sc9687_4, possible RNA-binding protein sequences from Drosophila melanogaster and Saccharomyces cerevisiae, respectively. The MRBP gene exists as a single copy in a mouse gemome as revealed by Southern blot analyses. Northern blot analyses have revealed that MRBP transcripts were expressed in a tissue-dependent manner, showing the highest expression level in mouse testis and the minor expression level in brain and spleen. It was also estimated that there were several isoforms of MRBP transcripts which might be generated by alternative splicing events in a tissue-specific manner. This diversified expression pattern suggests a bimodal regulation of the gene expression before and after transcription. Based on the differentiated and specified expression patterns, the MRBP is thought to play important and distinct roles in specific mouse tissues. The whole gene structure and detailed function of the translated protein remain to be studied further.