Cloning of shark RAG2 and characterization of the RAG1/RAG2 gene locus

SPECIFIC AIMSThe products of the recombination-activating genes (RAG) are required for the formation of active antigen receptor genes and thus are essential for expression of the vertebrate immune system. To elucidate conserved features of the RAG genes, we cloned the RAG2 gene from the sandbar shark (Carcharhinus plumbeus) and characterized the entire RAG1/RAG2 locus. We compared the shark sequences with those of higher vertebrates to determine phylogenetic homology and assess conservation of residues and segments required for function.PRINCIPAL FINDINGS1. Cloning of the shark RAG locusThe RAG2 gene is in close proximity to the RAG1 gene in species from teleosts to humans. Since we had previously cloned the shark RAG1 gene, our approach for cloning the shark RAG2 gene was by chromosomal walking from RAG1. The shark RAG2 gene is 9.4 kb from the 3′ end of the RAG1 gene coding region and contains a single 1560 bp open reading frame in the opposite transcriptional orientation. As with all other species, the ...