Isolation and characterization of two putative full-length Drosophila U4 small nuclear RNA genes.

U4 RNA is one of the abundant small nuclear RNAs implicated in the processing of the 3' -ends of premessenger RNAs (Berget, S. (1984) Nature 309, 179-182). Two potential U4 RNA genes were isolated from a Drosophila genomic DNA library and characterized. These genes, which were from different loci, had transcription and processing signals common to Drosophila U1 and U2 small nuclear RNA genes. One U4 gene locus also contained a downstream 5'-truncated U4 pseudogene. This is the first report in which putative full-length genes for U4 small nuclear RNA were isolated and characterized.