U1 small nuclear RNA-like sequences in human high molecular weight RNA

Human U1 small nuclear RNA synthesis was shown earlier to be very sensitive to UV radiation. This led us to test for the possible presence of U1 RNA-like sequences in large RNAs. Human RNA was analyzed in gel blots hybridized with U1 DNA probes. A high molecular weight, heterodisperse RNA population was detected, which hybridizes both to a U1 RNA-coding region single-stranded DNA probe, and to a U1 gene fragment that contains only 6 nucleotides of flanking sequence. These large RNAs can be hybrid selected using immobilized U1 DNA, and have an average size of several kilobases. Additional observations support the claims that the high molecular weight RNA hybridization signal is not an aggregation artifact and that it is sequence specific.