Article Abstract:
Seven alleles of the RNA-dependent ATPase Prp16 that are needed for the second stage of mRNA splicing in Saccharomyces cerevisiae were isolated. They are similar to the original allele Prp16-1 in that they permit splicing of introns with a mutant branch region (UACUAAC to UACUACC) by developing lariat intermediates at the mutant C nucleotide. The mechanism to reject inappropriately truncated substrates is under the genetic regulation of PRP16. Lowering the rate of ATP hydrolysis by Prp16 permits irregularly developed lariat intermediates longer time to go through the productive instead of the reject branch of this pathway.
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Article Abstract:
Adenosine triphosphate (ATP) and the protein components of the spliceosome play an important role in RNA rearrangements. ATPases unwind short RNA duplexes by functioning as a nonprocessive motor in splicing proofreadng steps. The spliceosome rearranges in a highly ordered and stepwise manner wherein many of the assembly steps relate to changes in RNA:RNA interactions. These interactions are depicted by powerful approaches, including phylogenetics, genetics and photochemical cross-linking procedures.
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Article Abstract:
Nuclear export signals (NESs) mediate nuclear protein export, although the method of transport is not well understood. CRM1 was found to be an essential mediator of nuclear protein export in yeast, following studies of a novel protein export assay in S. cerevisae. Crm1p has homology to importin beta-like transport factors and can intereact with the NES motif and the Ran GTPase.
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