Snurposome

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A snurposome is a granular structure in the nuclei of amphibian oocytes. Snurposomes contain snRNPs and are divided into the subtypes A, B, and C. A B snurposome is composed of thousands of particles which have diameters between 20 and 30 nanometers. [1] B snurposomes may be forms of splicing speckles. [2]

snRNPs, or small nuclear ribonucleoproteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. The action of snRNPs is essential to the removal of introns from pre-mRNA, a critical aspect of post-transcriptional modification of RNA, occurring only in the nucleus of eukaryotic cells. Additionally, U7 snRNP is not involved in splicing at all, as U7 snRNP is responsible for processing the 3′ stem-loop of histone pre-mRNA.

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Cajal body A class of nuclear body, first seen after silver staining by Ramon y Cajal in 1903, enriched in small nuclear ribonucleoproteins, and certain general RNA polymerase II transcription factors

Cajal bodies (CBs) also coiled bodies, are spherical sub-organelles of 0.3–1.0 µm in diameter found in the nucleus of proliferative cells like embryonic cells and tumor cells, or metabolically active cells like neurons. In contrast to cytoplasmic organelles, CBs lack any phospholipid membrane which would separate their content, largely consisting of proteins and RNA, from the surrounding nucleoplasm. They were first reported by Santiago Ramón y Cajal in 1903, who called them nucleolar accessory bodies due to their association with the nucleoli in neuronal cells. They were rediscovered with the use of the electron microscope (EM) and named coiled bodies, according to their appearance as coiled threads on EM images, and later renamed after their discoverer. Research on CBs was accelerated after discovery and cloning of the marker protein p80/Coilin. CBs have been implicated in RNA-related metabolic processes such as the biogenesis, maturation and recycling of snRNPs, histone mRNA processing and telomere maintenance. CBs assemble RNA which is used by telomerase to add nucleotides to the ends of telomeres.

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U1 spliceosomal RNA

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U7 small nuclear RNA

The U7 small nuclear RNA is an RNA molecule and a component of the small nuclear ribonucleoprotein complex. The U7 snRNA is required for histone pre-mRNA processing.

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The Centre for Gene Regulation and Expression, located within the School of Life Sciences, University of Dundee, pioneers new approaches in the field of gene expression and chromosome biology. Previously part of the Dundee Biocentre and receiving significant Wellcome Trust funding from 1995 onwards, it was awarded Wellcome Trust Centre status in 2008. Professor Tom Owen-Hughes is the Centre’s Director.

David L. Spector American cell biologist

David L. Spector is a cell and molecular biologist best recognized for his research on gene expression and nuclear dynamics. He is currently a Professor at Cold Spring Harbor Laboratory (CSHL) and head of the Gene Regulation and Cell Proliferation program of the CSHL Cancer Center. Since 2007, he has served as Director of Research of CSHL.

References

  1. Gall, J. G.; Bellini, M; Wu, Z; Murphy, C (1999). "Assembly of the Nuclear Transcription and Processing Machinery: Cajal Bodies (Coiled Bodies) and Transcriptosomes". Molecular Biology of the Cell. 10 (12): 4385–4402. doi:10.1091/mbc.10.12.4385. PMC   25765 Lock-green.svg. PMID   10588665.
  2. Lamond, Angus I.; Spector, David L. (2003). "Nuclear speckles: A model for nuclear organelles". Nature Reviews Molecular Cell Biology. 4 (8): 605. doi:10.1038/nrm1172. PMID   12923522. Left-hand column, page 607.
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