IDENTIFICATION OF NOVEL EXONS 3' TO THE HUMAN SNRPN GENE

The gene for the small nuclear ribonucleoprotein N (SNRPN) maps to hum an chromosome 15 and has 10 exons. Using cDNA cloning, direct cDNA sel ection, and exon connection reverse transcriptase (RT)-PCR, we have id entified three novel 3' exons of SNRPN, which have no protein coding p otential. Like the other SNRPN exons, the novel exons are expressed fr om the paternal allele only. In contrast to several cDNA clones and RT -PCR products, however, the 3.4-kb transcript detected by Northern blo t hybridization with a probe for the novel exons does not contain SNRP N. It is possible that the steady-state RNA observed in fetal tissues and in adult testis, ovary, brain, and muscle is initiated at an as ye t unidentified transcription start site downstream of SNRPN or is gene rated by endonucleolytic cleavage of a precursor transcript, as has be en shown for another imprinted gene, the insulin-like growth factor II gene. (C) 1997 Academic Press.