U7 small nuclear RNA in C snurposomes of the Xenopus germinal vesicle.
AUTOR(ES)
Wu, C H
RESUMO
In the amphibian germinal vesicle small nuclear RNAs (snRNAs) occur in morphologically distinct structures called snurposomes. Three types (A, B, and C) have been distinguished on the basis of cytological appearance and snRNA composition. C snurposomes in Xenopus are spherical bodies ranging in diameter from < 1 microns to about 10 microns. They stain intensely with antibodies against trimethylguanosine and the small nuclear ribonucleoprotein-specific Sm antigen but give weak or negative in situ hybridization reactions for the snRNAs involved in pre-mRNA splicing (U1, U2, U4, U5, and U6). We show here that C snurposomes in the Xenopus germinal vesicle contain U7 snRNA, an snRNA of low abundance involved in processing the 3' end of histone pre-mRNA. Xenopus U7 is 58 nucleotides long and is capped at the 5' end with trimethylguanosine. C snurposomes are often associated with B snurposomes, which contain the splicing snRNAs but not U7; B and C snurposomes together constitute a morphologically complex structure known as a sphere or sphere organelle. Although most spheres and C snurposomes are extrachromosomal, a few are attached at the histone gene loci on chromosomes 8, 9, and 16. Because they contain U7 snRNA and occur at the sites of histone pre-mRNA synthesis, C snurposomes presumably play a role in processing histone transcripts.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=46907Documentos Relacionados
- Cloning and characterization of the Drosophila U7 small nuclear RNA
- Functional analysis of the sea urchin U7 small nuclear RNA.
- The cDNA sequences of the sea urchin U7 small nuclear RNA suggest specific contacts between histone mRNA precursor and U7 RNA during RNA processing.
- Assembly, nuclear import and function of U7 snRNPs studied by microinjection of synthetic U7 RNA into Xenopus oocytes.
- Stable alteration of pre-mRNA splicing patterns by modified U7 small nuclear RNAs