FIG. 4.

One fate of long dsRNAs in the nucleus. Duplex RNAs produced by antisense transcription or transcriptional readthrough are promiscuously edited by ADAR enzymes, generating RNAs with extensive adenosine-to-inosine modifications. These molecules are bound tightly and cooperatively to a nuclear matrix-associated complex of p54nrb, PTB-associated splicing factor, and matrin 3, which prevents their export to the cytoplasm (433). RNAs with only one or a few inosines are not tightly bound and are allowed to leave the nucleus.