Abstract
| - Genomic clones containing genes for 4.5S RNAI, which is an abundant small nuclear RNA found in rodent cells, were obtained from a rat genomic library. Thirty-four clones that formed RNase A resistant hybrids with 3′-end-labeled 4.5S RNAI were isolated, and seven of them (clones λI39, λI41, λI42, λI51, λI106, λI123 and λI154 ) were characterized by sequencing and in vitro transcription. Clones λI41 and λI123 carry one and two genes, respectively, with identical sequences to that of 4.5S RNAI and are actively transcribed in vitro. However, the other five clones contain sequences that seem to be pseudogenes for 4.5S RNAI, since they have nucleotide substitutions or deletions in the sequence corresponding to 4.5S RNAI or are not transcribed. Four clones (λI39, λI42, λI106 and λI154) were found to have 13-18 nucleotide-long direct repeats flanking the 4.5S RNAI sequences. The genomic organization of the genes and their related sequences is discussed.
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