The structure and expression of the Salmo salar Ran gene

The Ran protein is a highly conserved GTPase factor of the Ras-family of proteins. It is involved in the transport of proteins and RNA through the nuclear pores. cDNA sequences of Ran genes from different organisms are available but no vertebrate genomic sequence as yet. We have isolated a genomic cosmid clone of the Ran1 gene of Atlantic salmon (Salmo salar) and found that the gene is about 2.2 kb and has got 5 introns. Its gene structure was compared to those of Caenorhabditis elegans and Arabidopsis thaliana and one intron was found to be conserved in position. Two different Ran transcripts were identified in salmon, indicating that there are two Ran genes, Ran1 and Ran2. Both transcripts were found in all ten salmon tissues tested, though Ran1 to a higher degree.