Imaging of RNA-Protein Interactions in Splicing Complexes with Dark-Field STEM

Sibbald, Mark J. J. B.; Carlemalm, Eric; Beer, Monika; Sproat, Brian S.

doi:10.1006/jsbi.1993.1011

Cited by 6 publications

(2 citation statements)

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“…Secondly, the dimensions of spliceosomes and snRNPs make it unlikely that more than one complete spliceosome is present in an NTS complex. Whole spliceosomes or assembly intermediates have been analyzed by electron microscopy in Drosophila (Osheim et al ., 1985; Beyer and Osheim, 1988), yeast (Clark et al ., 1988) and human cells (Reed et al ., 1988; Sibbald et al ., 1993; Furman and Glitz, 1995). The dimensions of the ellipsoid or ovoid discs varied between 18–25 nm × 24–60 nm (compare to dimensions of NTS complexes above).…”

Section: Discussionmentioning

confidence: 99%

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In situ transcription and splicing in the Balbiani ring 3 gene

et al. 2001

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The Balbiani ring 3 (BR3) gene contains 38 introns, and more than half of them are co-transcriptionally excised. We have determined the in situ structure of the active BR3 gene by electron tomography. Each of the 20±25 nascent transcripts on the gene is present together with splicing factors and the RNA polymerase II in a nascent transcript and splicing complex, here called the NTS complex. The results indicate that extensive changes in overall shape, substructure and molecular mass take place repeatedly within an NTS complex as it moves along the gene. The volume and calculated mass of the NTS complexes show that, maximally, one complete spliceosome is assembled on the multi-intron transcript at any given time point. The structural data show that the spliceosome is not a structurally well-de®ned unit in situ and that the C-terminal domain of the elongating RNA polymerase II cannot carry spliceosomal components for all introns in the BR3 transcript. Our data indicate that spliceosomal factors are continuously added to and released from the NTS complexes during transcription elongation.

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Section: Discussionmentioning

confidence: 99%

“…Spliceosomes assembled in vitro have been investigated by electron microscopy in yeast (Clark et al ., 1988) and in mammals (Reed et al ., 1988; Sibbald et al ., 1993; Furman and Glitz, 1995). Large complexes, apparently consisting of several spliceosomes, have been purified from mammalian nuclei (Sperling et al ., 1997).…”

Section: Introductionmentioning

confidence: 99%