Nucleotide sequence of small polyadenylated B2 RNA

Area of Science:

• Molecular Biology
• Genomics
• RNA Biology

Background:

• Small RNA molecules play crucial roles in gene regulation.
• The B2 repetitive sequence is abundant in the mouse genome.
• RNA polymerase III transcribes non-coding RNAs.

Purpose of the Study:

• To elucidate the structure of small B2 RNA molecules.
• To investigate the genomic origin and processing of B2 RNA.
• To explore the potential significance of B2 RNA in cellular processes.

Main Methods:

• Construction of a cDNA library from low-molecular-weight cytoplasmic poly(A)+RNA.
• Selection of clones hybridizing to the B2 sequence.
• DNA sequencing of selected clones.

Main Results:

• Small B2 RNA molecules contain B2 sequences followed by a poly(A) tract.
• B2 RNA sequences exhibit 3-10% variation, similar to genomic B2 copies.
• Most B2 RNA molecules initiate transcription at the beginning of genomic B2 sequences.
• Poly(A) tail length is comparable to mRNA, suggesting post-transcriptional addition.
• Additional sequences were observed in some clones, potentially due to RNA polymerase III terminator lesions.

Conclusions:

• Small B2 RNA is transcribed from numerous distinct B2 sequences within the genome.
• The poly(A) tails are likely added post-transcriptionally.
• Variations in B2 RNA structure may arise from transcriptional termination events.
• Further research is needed to understand the functional significance of B2 sequences and small B2 RNA.