Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heterogeneous nuclear ribonucleic acid (hnRNA) molecules in eucaryotic cell nuclei associate with a well-defined group of abundant, highly conserved proteins to form heterogeneous nuclear ribonucleoproteins (hnRNP). The exact manner in which these 30S complexes assemble on nuclear transcripts, however, has not been well documented. To determine whether any site selectivity in the formation of hnRNP can be detected (e.g., preferential recognition of intervening sequences or of premessage regions), we investigated the distribution of 30S hnRNP on a particular nuclear RNA, the polyoma virus late transcript. Hybridization studies showed not only that the majority of polyoma late nuclear RNA sequences can be isolated in the form of 30S complexes, but that the RNP were located equally on intervening sequences and premessage portions of the transcript. The latter conclusion was confirmed by ribonuclease T1 oligonucleotide fingerprint analysis of polyoma virus-specific RNA recovered from native 30S complexes. However, fingerprint analysis of the small segments of viral RNA in the 30S fraction that survived extensive ribonuclease treatment revealed that oligonucleotides corresponding to intervening sequences were preferentially lost. We discuss these findings in relation to the structure of 30S hnRNP and their function in RNA biogenesis.
Mol Cell Biol 1981 Jan
PMID:Arrangement of 30S heterogeneous nuclear ribonucleoprotein on polyoma virus late nuclear transcripts. 610 Sep 58

To demonstrate the affinity of RNA-containing polyribosomal components (isolated from L5178y cells) to microtubules, microtubule protein was attached to an insoluble matrix. In contrast to ribosomes, poly(A)(+)mRNA and poly(A)-RNP were found to bind to the matrix. Using synthetic polyribonucleotides, no significant differences in the binding properties of single- and double stranded polymers of different base composition to microtubule protein were observed. However, binding is dependent on the size of the polymer; a minimal chain length of 12 nucleotide units is required.
Mol Biol Rep 1982 Nov 30
PMID:Interaction of polyribosomal components and polyribonucleotides with microtubule proteins. 613 77

Free cytoplasmic 40S mRNP particles from rat liver were treated with EDTA and separated into two populations of RNP particles with sedimentation maxima of 20S and 35S, respectively. A characteristic set of distinct scRNAs is found for 20S and 35S RNP particles. The sequences of two of the most abundant scRNAs from 20S RNP particles with chain lengths of 104 (alpha 1-RNA) and 124 (beta 1-RNA) nucleotides, respectively, are presented. alpha 1-RNA shows a high sequence homology to the 3'-end of 18S rRNA. Since alpha 1-RNA carries a cap, it cannot be a degradation product of 18S rRNA. The beta 1-RNA is strongly post-transcriptionally modified, but uncapped. When the individual scRNAs of 20S and 35S RNP particles isolated from preparative polyacrylamide gels were assayed for their capability to inhibit in vitro protein synthesis, several potent translational inhibitory RNAs were detected. Particularly, the scRNAs of 147,203 and 263 nucleotide length associated with the 35S RNP particles turned out to be strong inhibitors of protein synthesis.
Mol Biol Rep 1983 May
PMID:Small cytoplasmic RNAs from rat liver mRNP particles. Studies on their structure and function. 619 10

U1 small nuclear RNA is thought to be involved in messenger RNA splicing by binding to complementary sequences in pre-mRNA. We have investigated intermolecular base-pairing between pre-mRNA (hnRNA) and U1 small nuclear RNA by psoralen crosslinking in situ, with emphasis on ribonucleoprotein structure. HeLa cells were pulse-labeled with [3H]uridine under conditions in which hnRNA is preferentially labeled. Isolated nuclei were treated with aminomethyltrioxsalen , which produces interstrand crosslinks at sites of base-pairing between hnRNA and U1 RNA. hnRNA-ribonucleoprotein (hnRNP) particles were isolated in sucrose gradients containing 50% formamide, to dissociate non-crosslinked U1 RNA, and then analyzed by immunoaffinity chromatography using a human autoantibody that is specific for the ribonucleoprotein form of U1 RNA (anti-U1 RNP). After psoralen crosslinking, pulse-labeled hnRNA in hnRNP particles reproducibly bound to anti-U1 RNP. The amount of hnRNA bound to anti-U1 RNP was reduced 80 to 85% when psoralen crosslinking of nuclei was omitted, or if the crosslinks between U1 RNA and hnRNA were photo-reversed prior to immunoaffinity chromatography. Analysis of the proteins bound to anti-U1 RNP after crosslink reversal revealed polypeptides having molecular weights similar to those previously described for U1 RNP. These proteins did not bind to control, non-immune human immunoglobulin G. These results indicate that the subset of nuclear U1 RNA that is base-paired with hnRNA at a given time in the cell is a ribonucleoprotein. This raises the possibility that these proteins, as well as U1 RNA itself, may participate in pre-mRNA splice site recognition by U1 RNP.
J Mol Biol 1984 Apr 05
PMID:Ribonucleoprotein organization of eukaryotic RNA. XXX. Evidence that U1 small nuclear RNA is a ribonucleoprotein when base-paired with pre-messenger RNA in vivo. 620 17

The C proteins (C1 and C2) are major constituents of the 40S subparticle of heterogeneous nuclear ribonucleoprotein complexes (hnRNPs) (Beyer, A.L., M.E. Christensen, B.W. Walker, and W.M. LeStourgeon, 1977, Cell, 11:127-138) and are two of the most prominent proteins that become cross-linked by ultraviolet light to heterogeneous nuclear RNA (hnRNA) in vivo. Studies are described here on the characterization of the C proteins in vertebrate cells using monoclonal and polyclonal antibodies. Monoclonal antibodies to genuine RNP proteins, including the C proteins, were obtained by immunizing mice with purified complexes of poly(A)+ hnRNA and poly(A)+ mRNA with their contacting proteins in vivo obtained by ultraviolet cross-linking the complexes in intact cells (Dreyfuss, G., Y.D. Choi, and S.A. Adam, 1984, Mol. Cell. Biol., 4:1104-1114). One of the monoclonal antibodies identified the C proteins in widely divergent species ranging from human to lizard. In all species examined, there were two C proteins in the molecular weight range of from 39,000 to 42,000 for C1, and from 40,000 to 45,000 for C2. The two C proteins were found to be highly related to each other; they were recognized by the same monoclonal antibodies and antibodies raised against purified C1 reacted also with C2. In avian, rodent, and human cells the C proteins were phosphorylated and were in contact with hnRNA in vivo. Immunofluorescence microscopy demonstrated that the C proteins are segregated to the nucleus. Within the nucleus the C proteins were not found in nucleoli and were not associated with chromatin as seen in cells in prophase. These findings demonstrate that C proteins with similar characteristics to those in humans are ubiquitous components of hnRNPs in vertebrates.
 ...
PMID:Monoclonal antibody characterization of the C proteins of heterogeneous nuclear ribonucleoprotein complexes in vertebrate cells. 620 85

Active transcription units are visualized in the electron microscope and the ribonucleoprotein structure of nascent transcripts is analyzed by the technique of RNP fibril mapping. This ultrastructural approach has demonstrated that the nonrandom RNP structure observed is correlated with, and perhaps mediates, a specific RNA processing event.
Mol Biol Rep 1983 May
PMID:Ultrastructural analysis of the ribonucleoprotein structure of nascent hnRNA. 641 68

Antinuclear autoantibodies are a hallmark of autoimmune diseases. The RNP, Sm and SS-B nuclear antigens from calf thymus in whole tissue, nuclear extracts and fractions have been studied by using different techniques including immunodiffusion, counterimmunoelectrophoresis and protein blotting. Such studies were done in order to obtain a precise characterization of the polypeptide components of those antigens. From our results it can be established that: one 69.8 Kd polypeptide (for whole tissue and nuclei) and a number of well-defined 32-38-Kd polypeptides (for nuclear extracts and ammonium sulfate fractions) show an antigenic character against anti-RNP sera; anti-Sm sera from different patients show in all cases a variable component of antigenic polypeptides, including one 28.8, 29.7 Kd doublet and two singlets of 14.8 and 11.0 Kd; and a 52.0-Kd SS-B antigenic polypeptide is found for whole tissue, which is gradually degraded in nuclei and nuclear extracts to a more stable 47.1-Kd polypeptide.
Mol Immunol 1984 Aug
PMID:Characterization of antigenic polypeptides of the RNP, Sm and SS-B nuclear antigens from calf thymus. 643 Dec 69

A nuclear p53/55 protein kinase has been isolated from nuclear ribonucleoprotein particles from human tumor cells. The enzyme was purified approximately 2200-fold cell nuclei by sequential ribonuclease digestion of the RNP particles, DEAE cellulose and phosphocellulose chromatography. The kinase which was cAMP independent, catalyzed the phosphorylation of rabbit muscle glycogen synthase in the amino terminal domain, and conversion of the I to D form. The D synthase had a phosphorylation stoichiometry of 8 moles 32P per mole of synthase subunit with maximal specificity for ATP as phosphate donor; its Km was 30 microM. An antinucleolar antibody inhibited enzyme activity by 80%. Substrates for most other kinases were inactive. The kinase was essentially unaffected by the Walsh inhibitor, EGTA, regulatory subunits of protein kinase, calmodulin, trifluoperazine or heparin. Its activity was lost at 1 mM polyamine, but was enhanced 3-fold by MnCl2 and 4- to 9-fold by deoxymononucleotides. The nuclei of HeLa cells contained 64% of the total kinase of which 64% of the total kinase of which 11% were in nucleoli; the specific activity of the nucleolar kinase was twice that of the nuclear supernatant and four times that of the cytoplasmic kinase. These results indicate that nucleolar ribonucleoprotein particles of human tumor cells contain a cAMP-independent protein kinase which is similar to glycogen synthase kinase.
Mol Cell Biochem 1984 Aug
PMID:Purification of p53/55 kinase from nuclear ribonucleoproteins of Namalwa cells. 643 81

Electron microscopic examination of chromatin has indicated that there are two major classes of ribosomal transcription units (rTUs) in Drosophila melanogaster. (a) a standard class which is about 8 kb in length and (b) a longer class (up to 15 kb) which has been hypothesized as having an intron in the 28S region of the gene. On rare occasions, we have observed a third class of TUs, which we term pseudo rTUs (or pseudo ribosomal RNA genes), distributed among the standard rTUs. Pseudo rTUs are composed of short fiber arrays with clear gradients in their RNP fiber lengths. The pseudo rTUs observed in egg chambers and blastoderm embryos are 4.1 +/- 0.58 kb in length and are found in tandem with non-transcribed spacer regions. The lengths of the non-transcribed spacer regions are found in 2 classes: one at 4.94 +/- 1.78 kb and the other at 19.28 +/- 2.11 kb. The present information suggests that these pseudo rTU fiber arrays are ribosomal in origin as their RNP fibers cross-react with antibodies raised against Drosophila ribosomal proteins. The pattern of distribution of D. melanogaster ribosomal protein L4 on RNP fibers in standard rTUs is compared with that in pseudo rTUs. This was determined by a novel approach involving the use of electron microscopic spreads of rTUs to which had been added IgGs labelled with polymethacrylate spheres. Pseudo ribosomal RNA genes are present in both the X (6%) and in the Y (6%) ribosomal chromatin as is indicated by their existence in nurse cells of both Oregon-R females, and females of the genotype sc4sc8/sc4sc8/y+Y.
Mol Gen Genet 1981
PMID:The in vivo expression of pseudo ribosomal RNA genes in Drosophila melanogaster. 679 8

In this article, we discuss our attempts to establish the existence in the cytoplasm of regulatory molecules involved in translational control. Our studies have revealed the presence of cAMP independent protein kinase in the free mRNP complex capable of phosphorylating a Mr = 38 000 polypeptide, also part of the same complex. Both the kinase and the acceptor protein were found also as free proteins in the cytoplasmic pool. This kinase has been shown to be distinct from the heme regulated enzyme that phosphorylates the small subunit of eIF-2. Other regulatory molecules include small molecular weight RNAs found as part of an RNP complex. A 4S fraction isolated from this complex inhibited the translation of both capped and uncapped mRNAs in a cell-free protein synthesizing system. The biological role of the protein kinase and the 4S RNA fraction is considered.
Mol Cell Biochem 1981 Nov 13
PMID:Cytoplasmic nonpolysomal ribonucleoprotein complexes and translational control. 679 20


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>