In eukaryotes, pre-mRNA exons are interrupted by large noncoding introns. Alternative selection of exons and nucleotide-exact removal of introns are performed by the spliceosome, a highly dynamic macromolecular machine. U4/U6.U5 tri-snRNP is the largest and most conserved building block of the spliceosome. By 3D electron cryomicroscopy and labeling, the exon-aligning U5 snRNA loop I is localize...

In large ribonucleoprotein machines, such as ribosomes and spliceosomes, RNA functions as an assembly scaffold as well as a critical catalytic component. Protein binding to the RNA scaffold can induce structural changes, which in turn modulate subsequent binding of other components. The spliceosomal U4/U6 di-snRNP contains extensively base paired U4 and U6 snRNAs, Snu13, Prp31, Prp3 and Prp4, s...

Purpose. The small nuclear ribonucleoprotein 200 kDa (SNRNP200) gene is a fundamental component for precursor message RNA (pre-mRNA) splicing and has been implicated in the etiology of autosomal dominant retinitis pigmentosa (adRP). This study aims to determine the consequences of knocking down Snrnp200 in zebrafish. Methods. Expression of the Snrnp200 transcript in zebrafish was determined via...

A dicistronic minigenome containing the M-F gene junction was used to determine the role of the simian virus 5 (SV5) intergenic regions in transcription. The M-F junction differs from the other SV5 junctions by having a short M gene end U tract of only four residues (U4 tract) and a 22-base M-F intergenic sequence between the M gene end and F gene start site. Replacing the 22-base M-F intergeni...

Four halotolerant fungal isolates originating from the saltwater Lake Urmia in Iran were selected during a screening program for salt resistance and α-amylase activity. The isolates were identified based on sequencing the ITS region and a part of the β-tubulin gene, as Penicillium chrysogenum (isolate U1; CBS 132820), Fusarium incarnatum (isolate U2; CBS 132821), and Penicillium polonicum (isol...

The distribution of U1, U2, U4, U5 and U6 small nuclear ribonucleoproteins (snRNPs) and interchromatin granules (IGs) was studied by electron-microscopic immunocytochemistry (EMI) in early 2-cell mouse embryos at the onset of embryonal transcription. The localization of these antigen structures was evaluated with respect to nucleoplasmic ribonucleoprotein (RPN) regions consisting of interchroma...

The highly conserved splicing factor Prp8 has been implicated in multiple stages of the splicing reaction. However, assignment of a specific function to any part of the 280-kD U5 snRNP protein has been difficult, in part because Prp8 lacks recognizable functional or structural motifs. We have used a large-scale screen for Saccharomyces cerevisiae PRP8 alleles that suppress the cold sensitivity ...