Transcription termination and processing of transcripts from tRNA‐related Xenopus satellite DNA sequences

Abstract

Nucleotide sequence homologies have been found between the transcriptional unit of a Xenopus laevis satellite DNA containing 1037‐bp monomeric repeats and tRNA‐coding genes. Since the tRNA‐homologous region forms only part of the transcriptional unit, we have analyzed the size of transcripts being made after injection of cloned DNA into Xenopus oocyte nuclei. Incubation for 6 h mainly results in three RNA species comprising 130, 183 and 196 nucleotides, which originate at the same initiation site but terminate at different T stretches. Longer incubation reveals a complex pattern of smaller RNAs most likely resulting from 3′‐end processing of primary transcripts. All these RNAs are related to tRNA, since they contain the tRNA‐homologous region which is close to the 5′ end of the transcription unit.