HnRNP particles

Venrooij, Walther J. van; Janssen, Dick B.

doi:10.1007/bf00775172

Cited by 46 publications

(22 citation statements)

References 95 publications

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“…As it is being transcribed, heterogeneous nuclear RNA (hnRNA) associates with proteins to form heterogeneous nuclear ribonucleoprotein (hnRNP) complexes (1,2). These complexes can be seen in electron micrographs of chromatin undergoing transcription as globular "beaded" structures along the length of newly transcribed RNA (3)(4)(5).…”

mentioning

confidence: 99%

A RNA helix-destabilizing protein is a major component of Artemia salina nuclear ribonucleoproteins.

Thomas¹,

Raziuddin²,

Sobota³

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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A major component of 30S heterogeneous nuclear ribonucleoprotein (hnRNP) particles from Artemia salina is HD40, a protein that has been characterized as a RNA helix-destabilizing protein [Marvil, D. K., As it is being transcribed, heterogeneous nuclear RNA (hnRNA) associates with proteins to form heterogeneous nuclear ribonucleoprotein (hnRNP) complexes (1, 2). These complexes can be seen in electron micrographs of chromatin undergoing transcription as globular "beaded" structures along the length of newly transcribed RNA (3-5). When nuclei are incubated at pH 8.0, nuclear RNP particles that sediment at 30-50 S are released, presumably as a result of the cleavage of nuclease-sensitive regions between the "beads" (6-8).Since hnRNP are probably involved in the processing of primary transcripts and in the generation of mRNA molecules, there is considerable interest in their structure and in the function of individual hnRNP proteins. There is a growing body of evidence that hnRNPs from many eukaryotic cells contain a class of basic polypeptides in the 30,000-40,000 molecular weight range that forms the core of the monomeric 30-50S hnRNP particles and, thus, may play a structural role in the organization of hnRNPs (9-11). Proteins within this class, regardless ofthe cell oforigin, are characterized by a high content of glycine, little or no cysteine, and the presence of the unusual amino acid dimethylarginine. There appear to be only a few polypeptides having different primary structures within this class, but extensive modifications after translation give rise to multiple protein bands upon isoelectric focusing (9,11). In rat brain and in mouse ascites cells, the NH2-terminal amino acid of all of the glycine-rich proteins is blocked (11, 12).We have obtained from extracts of dormant (undeveloped) cysts ofthe brine shrimp Artemia salina a homogeneous protein that is strikingly similar in amino acid composition and molecular weight to this class ofhnRNP proteins (13,14). The protein, designated HD40 to indicate that it is a helix-destabilizing protein with a molecular weight of40,000, binds to single-stranded (but not double-stranded) synthetic and natural polynucleotides and disrupts their residual secondary structure. The polynucleotides are maximally unwound at a stoichiometry of one HD40 per 12-15 nucleotides. The addition of HD40 in excess of this ratio results in the formation of globular structures or "beads" along the entire polynucleotide strand. These complexes are reduced in contour length with respect to the unfolded complexes obtained at a 1:12 stoichiometry, have an appearance similar to the beaded structure of hnRNPs, and are largely protected from degradation by nucleases (13,14). For these experiments, HD40 was purified on a preparative scale from extracts in which the nuclei had been broken.In this communication we show that HD40 is a major component of 30S RNP particles extracted from intact nuclei of developed A. salina cysts and that homogeneous HD40 binds to hnRNA fragments extracte...

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mentioning

confidence: 99%

A RNA helix-destabilizing protein is a major component of Artemia salina nuclear ribonucleoproteins.

Thomas¹,

Raziuddin²,

Sobota³

et al. 1981

Proc. Natl. Acad. Sci. U.S.A.

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“…The structural organization of heterogeneous nuclear RNA (hnRNA)(reviewed in 1 and 2) has been studied extensively in order to understand the mechanism of RNA processing and its regulatory role in the control of gene expression (3).All hnRNA,also those containing mRNA sequences, are associated with protein to form ribonucleoprotein particles (1,2,4). HnRNA-protein complexes, generally referred to as hnRNP particles, can be isolated from nuclei by extraction at elevated pH or by sonication.…”

Section: Introductionmentioning

confidence: 99%

“…The size of the isolated particles depends on the extent of ribonuclease degradation during the isolation procedure. Under nuclease free conditions large particles (polyparticles) Nucleic Acids Research can be recovered, whereas after mild nuclease degradation 30-40 S monoparticles accumulate (2,5). The polypeptide composition of the isolated complexes is also dependent on the isolation procedure.…”

Section: Introductionmentioning

confidence: 99%

“…The polypeptide composition of the isolated complexes is also dependent on the isolation procedure. Polypeptide compositions ranging from almost all non-histone nuclear proteins to a few distinct polypeptides have been reported (1,2,(6)(7)(8)(9)(10). The protein composition of purified monoDarticles, which are considered as structural building blocks of hnRNP, is relatively simple.…”

Section: Introductionmentioning

confidence: 99%

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Sequence dependent interaction of hnRNP proteins with late adenoviral transcripts

Eekelen¹,

Ohlsson²,

Philipson³

et al. 1982

Nucl Acids Res

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Irradiation with ultraviolet light was used to induce covalent linkage between hnRNA and its associated proteins in intact HeLa cells, late after infection with adenovirus type 2. Covalently linked hnRNA-protein complexes, containing polyadenylated adenoviral RNA, were isolated and their protein moiety characterized. Host 42,000 Mr hnRNP proteins proved to be the major proteins crosslinked to viral hnRNA. To investigate their possible involvement in RNA processing, the localization of these cross-linked polypeptides on adenoviral late transcripts was determined. Sequences of RNA around the attachment sites of the protein were isolated. After in vitro labeling they were hybridized to Southern blots of adeno DNA fragments. The hybridization patterns revealed that the 42,000 Mr polypeptides can be linked to adenoviral transcripts over the entire length of the RNA, corresponding to 16.2-91.5 m.u. of the viral genome. Fine mapping within the Hind III B region (16.8-31.5 m.u.) established, however, that the localization of the cross-linked polypeptides was not random in all parts of the transcript. Sequences around the third leader and the 3' part of the i-leader were overrepresented, whereas the regions encoding VA I and VA II RNA and the late region 1 mRNA bodies were underrepresented in the cross-linked RNA. Using genomic DNA fragments and a cDNA clone containing the tripartite leader it appeared that leader and intervening sequences were represented about equally in cross-linked RNA fragments. Although these results do not support the notion that introns or exons are specifically interacting with one RNP protein, they demonstrate that the 42,000 hnRNP proteins are non randomly positioned on the RNA sequence. INTRODUCTIONThe structural organization of heterogeneous nuclear RNA (hnRNA)(reviewed in 1 and 2) has been studied extensively in order to understand the mechanism of RNA processing and its regulatory role in the control of gene expression

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“…It is not clear whether this is due to a real heterogeneity in the ultrastructural organization of different RNA transcripts or to their high sensitivity to environmental conditions. Thus, it is difficult to 662 deduce the exact morphology of the nuclear RNP complexes, although different models have been proposed (18,29,31,34,37). The resolution of this problem may be facilitated by methods that allow ultrastructural observations of free nuclear RNP particles without their preliminary isolation and under minimal treatment of the nuclei.…”

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Ultrastructure of free ribonucleoprotein complexes in spread mammalian nuclei.

Tsanev¹,

Djondjurov²

1982

The Journal of Cell Biology

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Mouse erythroleukemia cell nuclei obtained by three different methods were spread for electron microscopy under low ionic conditions. It was found that this procedure allows the observation of free large ribonucleoprotein (RNP) complexes released from the nuclei during the centrifugation. The morphology of these complexes was readily affected by the conditions of cell treatment and spreading. Two extreme forms of free nuclear RNP structures were obtained, both consisting of spherical particles with diameters of ~17-20 nm. The first type was of loosened complexes of irregularly assembled particles interconnected with RNA fibrils. The second represented tightly packed particles forming mostly branched structures. The latter structures appeared to be closer to the native form of the nuclear RNP particles, differing from polyribosomes by their characteristic branching and stability in EDTA solutions.

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HnRNP particles

Cited by 46 publications

References 95 publications

A RNA helix-destabilizing protein is a major component of Artemia salina nuclear ribonucleoproteins.

A RNA helix-destabilizing protein is a major component of Artemia salina nuclear ribonucleoproteins.

Sequence dependent interaction of hnRNP proteins with late adenoviral transcripts

Ultrastructure of free ribonucleoprotein complexes in spread mammalian nuclei.

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