The gene encoding the small nuclear ribonucleoprotein-associated protein N is expressed at high levels in neurons

The highly homologous small nuclear ribonucleoprotein-associated proteins of the Sm group, human N and B/B', are derived from distinct, but similar genes. While the almost identical structural organization of the genes for N and B/B' suggests that they emerged from a common ancestral gene via a duplication event, they now reside on different chromosomes. In contrast to B (which is expressed in all tissues examined) and B' (which is widely expressed with the notable exception of the brain), results from in situ hybridization experiments showed that N is found predominantly in central neurons. Analysis of the transcriptional activity of the 5'-flanking sequences of the human N-encoded gene suggests that the cell-specific expression of N is achieved by selective repression of transcription by distal 5'-flanking sequences.