Modification of Sm small nuclear RNAs occurs in the nucleoplasmic Cajal body following import from the cytoplasm.

ABSTRACT: Biogenesis of functional spliceosomal small nuclear RNAs (snRNAs) includes the post-transcriptional covalent modification of numerous internal nucleotides. We have recently demonstrated that synthesis of 2'-O-methylated nucleotides and pseudouridines in the RNA polymerase II-synthesized Sm snRNAs is directed by sequence-specific guide RNAs. Here, we provide evidence supporting the notion that modification of Sm snRNAs occurs in nucleoplasmic Cajal bodies (CBs), where modification guide RNAs accumulate. We show that short fragments of Sm snRNAs are correctly and efficiently modified when targeted to CBs, but not when these same fragments are targeted to the nucleolus. We also demonstrate that internal modification of the U2 snRNA occurs exclusively after nuclear import of the newly assemble

SUBMITTER: Jady BE 

PROVIDER: S-EPMC154478 | biostudies-literature | 2003 Apr

REPOSITORIES: biostudies-literature