RABBIT RAG-2 UTRS - CHARACTERIZATION OF AN UNUSUALLY LARGE 3'-UNTRANSLATED REGION

We previously characterized the rabbit recombination activating gene-2 (RAG-2) coding region and a portion of the cDNA. Rabbit RAG-2 mRNA, h owever, was shown to be approximately twice as large as the predominan t form expressed in other vertebrate species, suggesting that it conta ined additional coding and/or untranslated regions (UTR). In this repo rt, we map and sequence the complete 5' and 3' UTRs of the rabbit RAG- 2 transcript and identify and sequence the genomic regions from which they are transcribed. The data show that, with the exception of a 300 nucleotide 5' UTR, almost all of the additional sequence belongs to th e 3' UTR and that the 3' UTR sequence is transcribed from a single lar ge exon that encodes most of the coding region and all of the 3' UTR. The 3' UTR contains four poly A signal sites, the last of which is clo sely followed by a GU-rich region. The rabbit 3' UTR has a high level of identity with the homologous region downstream of the human RAG-2 g ene but not with the mouse RAG-2 gene. The region of identity extends several hundred nucleotides beyond the transcribed region and terminat es in a series of dinucleotide (TG) repeats. The data are discussed in terms of RAG gene and 3' UTR function, regulation, and evolution.