Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cytoplasmic 10S ribonucleoprotein (iRNP) is a potent inhibitor of mRNA translation in vitro and contains a 4 S translation inhibitory RNA species (iRNA) (Sarkar, S., Mukherjee, A. K., and Guha, C. (1981) J. Biol. Chem. 256, 5077-5086). This ribonucleoprotein has now been resolved into protein and RNA components by DEAE-cellulose chromatography in the absence of both K+ and Mg2+ ions. These cations are required for maintaining the nucleoprotein structure of iRNP. Incubation of the dissociated protein and RNA components in the presence of K+ and Mg2+ at 35 degrees C reconstitutes a 10 S particle which is indistinguishable from native iRNP with respect to the elution profile by gel filtration, UV spectra, buoyant density, resistance to pancreatic RNase, and ability to inhibit exogenous mRNA translation in vitro. Chick muscle tRNA and globin mRNA could not form an RNP complex with the protein moieties of iRNP. The separated proteins, unlike iRNA and iRNP, do not inhibit mRNA translation. Their function may be to protect iRNA from ribonuclease digestion, since iRNP is ribonuclease-resistant. The ability to dissociate the iRNP particle and to specifically reconstitute it from the separated components indicates that it is a unique cellular entity which is distinct from other ribonucleoproteins.
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PMID:The translational inhibitor 10 S cytoplasmic ribonucleoprotein of chick embryonic muscle. Dissociation and reassociation. 728 68

Ro small ribonucleoprotein complexes (RoRNPs) are thought to comprise several proteins, including the 60-kD Ro and the 52-kD Ro proteins, and several small RNAs, designated Y RNAs. Although RoRNPs are fairly ubiquitous in nature, their precise composition remains unknown, their function has been elusive, and their intracellular localization has been controversial. We have analyzed HeLa cell extracts by glycerol density gradient fractionation in order to determine the distribution of the individual protein and RNA components of RoRNPs. We found that 52-kD Ro was not detectable in an RNP complex with the 60-kD protein under a variety of conditions. Pretreatment of cell extracts with ribonuclease affected gradient migration of the 60-kD but not the 52-kD protein, suggesting that the latter is not complexed with RNA. The migration of the hY RNAs in these gradients closely followed that of 60-kD and not 52-kD Ro. Immunofluorescence analysis of two different cell lines with monospecific antibodies against 52- and 60-kD proteins strongly suggests that these two proteins are not present on overlapping sets of structures in vivo. We conclude that the 52-kD Ro protein is not a detectable component of the RoRNP complex under these conditions despite its reactivity with Ro autoimmune antisera.
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PMID:Molecular composition of Ro small ribonucleoprotein complexes in human cells. Intracellular localization of the 60- and 52-kD proteins. 751 86

Evidence suggesting the presence in rat liver nuclear extracts of a new RNP complex of 70-110S has been provided [Hatzoglou, M., Adamtziki, E., Margaritis, L. and Sekeris, C.E (1985) Exp. Cell. Res. 157, 227-241]. Biochemical features unique to this RNP were its stability to salt and RNase digestion and the presence of a pair of polypeptides of 72/74 kDa. By producing antibodies against the 72/74 kDa polypeptides these proteins have been defined as integral components of the 70-110S RNP complex. They comprise two immunologically related polypeptides with an exclusively nucleoplasmic localization, giving a speckled pattern in a diffuse background, similar, but not identical, to the Sm antigen. The 70-110S RNP complex, referred to as large heterogeneous nuclear RNP (LH-nRNP), has a simple protein pattern that includes, in addition to the 72/74 kDa proteins, three stably associated polypeptides of apparent molecular size 110, 61 and 59 kDa. The bulk of its RNA component represents a discrete RNA population of 10-20S, belonging to a subset of the RNA detected within immunopurified HeLa hnRNP complexes. These RNA species are RNA polymerase II transcripts of greater stability relative to the bulk of hnRNA, containing oligo(A) or poly(A) sequences. Immunodepletion and/or antibody addition studies in HeLa splicing extracts using antibodies with specificity for the 72/74 kDa proteins revealed a rather strong inhibition of splicing activity, suggesting participation of the LH-nRNP complex in in vitro splicing.
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PMID:Two immunologically related polypeptides of 72/74 kDa specify a novel 70-100S heterogeneous nuclear RNP. 765 36

Cleavage of the yeast pre-rRNA at site A(2) in internal transcribed spacer 1 (ITS1) requires multiple snoRNP species, whereas cleavage at site A(3),located 72 nt 3' in ITS1, requires Rnase MRP. Analyses of mutations in the pre- rRNA have revealed an unexpected link between processing at A(2) and A(3). Small substitution mutations in the 3' flanking sequence at A(2) inhibit processing at site A(3), whereas a small deletion at A(3) has been shown to delay processing at site A(2). Moreover, the combination of mutations in cis at both A(2) and A(3) leads to the synthesis of pre-rRNA species with 5' ends within the mature 18S rRNA sequence, at sites between + 482 and + 496. The simultaneous interference with an snoRNP processing complex at site A(2) and an Rnase MPRP complex at site A(3) may activate a pre-rRNA breakdown pathway. The same aberantpre-rRNA species are observed in strains with mutations in the RNA component of Rnase MRP, consistent with interactions between the processing complexes. Furthermore, genetic depletion of the snoRNA, snR30, has been shown to affect the coupling between cleavage by Rnase MRP and subsequent exonuclease digestion.We conclude that an sno-RNP-dependent processing complex that is required for A(2) cleavage and that recognizes the 3' flanking sequence at A(2), interacts with the RNase MRP complex bound to the pre-rRNA around site A(3).
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PMID:Processing of the yeast pre-rRNA at sites A(2) and A(3) is linked. 884 97

RNase MRP is a ribonucleoprotein originally identified on the basis of its ability to cleave RNA endonucleolytically from origins of mitochondrial DNA replication, rendering it a likely candidate for a role in priming leading-strand synthesis of mtDNA. In addition, a nuclear role for RNase MRP has been identified in yeast (Saccharomyces cerevisiae) ribosomal RNA processing. Consistent with a duality of function, RNase MRP has been localized to both mitochondria and nucleoli by in situ techniques. The RNA component of this ribonucleoprotein has been characterized from several different species. We previously cloned the gene for Xenopus laevis MRP RNA and showed that RNase MRP RNA is differentially expressed during amphibian development; in addition, the microinjected X. laevis RNase MRP RNA gene is correctly and efficiently transcribed in vivo. This article presents an analysis of the intracellular movement of in vivo-transcribed RNase MRP RNA in microinjected mature X. laevis oocytes. Although X. laevis MRP RNA is assembled into a ribonucleoprotein form and transported in an expected manner, human and mouse MRP RNAs exhibit markedly different transport patterns even though they are highly conserved in primary sequence. Furthermore, the only currently assigned protein (Th autoantigen) binding site in MRP RNA can be deleted without loss of nuclear export capacity. These results indicate that subtle determinants must exist for nucleocytoplasmic partitioning of this RNP and that the conserved Th autoantigen binding region appears unnecessary for the transit of in vivo-transcribed MRP RNA to the cytoplasm of mature X. laevis oocytes.
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PMID:Subtle determinants of the nucleocytoplasmic partitioning of in vivo-transcribed RNase MRP RNA in Xenopus laevis oocytes. 888 39

Anti-Sm Abs recognize Sm core proteins B'/B, D, E, F, and G, shared by U1, U2, U4-6, and U5 small nuclear ribonucleoproteins (snRNPs), while anti-nuclear ribonucleoprotein Ag (nRNP) Abs recognize the U1 RNP-specific 70K, A, and C proteins. However, although the autoimmune response to U1 snRNPs involves all components of the particle, not all are recognized equally. For example, all human anti-nRNP sera contain Abs against native U1-C, in contrast to their absence in MRL/lpr mice. In this study, autoantibody recognition of native U1 snRNPs was investigated by dissociating the particle into four components (U1-70K, U1-A, U1-C, and the Sm core particle) using 1 M MgCl2 or ribonuclease treatment. As expected, human anti-Sm and MRL/lpr sera immunoprecipitated only the Sm core proteins, and human anti-nRNP/Sm sera immunoprecipitated the Sm core proteins plus U1-C under both conditions. However, although human anti-nRNP sera immunoprecipitated U1-C when U1 snRNPs were dissociated before Ab binding, they unexpectedly immunoprecipitated the Sm core proteins when Abs were bound before dissociation. This apparent paradox was explained by the stabilizing effects of anti-nRNP sera on interactions of U1-C with the Sm core particle. All human anti-nRNP sera contained high levels of autoantibodies that prevent dissociation of U1-C from the U1 snRNP. These Abs were absent in MRL/lpr mice. Human autoimmune sera may prevent dissociation by recognizing the quaternary structure of the U1-C-Sm core protein complex or by altering its conformation. Stabilization of U1 snRNPs by autoantibodies could influence Ag processing and presentation, possibly with important effects on the development of autoimmunity to U1 snRNPs.
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PMID:Human anti-nuclear ribonucleoprotein antigen autoimmune sera contain a novel subset of autoantibodies that stabilizes the molecular interaction of U1RNP-C protein with the Sm core proteins. 914 22

In addition to the conserved and well-defined RNase H domain, eukaryotic RNases HI possess either one or two copies of a small N-terminal domain. The solution structure of one of the N-terminal domains from Saccharomyces cerevisiae RNase HI, determined using NMR spectroscopy, is presented. The 46 residue motif comprises a three-stranded antiparallel beta-sheet and two short alpha-helices which pack onto opposite faces of the beta-sheet. Conserved residues involved in packing the alpha-helices onto the beta-sheet form the hydrophobic core of the domain. Three highly conserved and solvent exposed residues are implicated in RNA binding, W22, K38 and K39. The beta-beta-alpha-beta-alpha topology of the domain differs from the structures of known RNA binding domains such as the double-stranded RNA binding domain (dsRBD), the hnRNP K homology (KH) domain and the RNP motif. However, structural similarities exist between this domain and the N-terminal domain of ribosomal protein L9 which binds to 23 S ribosomal RNA.
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PMID:NMR structure of the N-terminal domain of Saccharomyces cerevisiae RNase HI reveals a fold with a strong resemblance to the N-terminal domain of ribosomal protein L9. 1044 44

For the first time small nuclear ribonucleoprotein particles (alpha-RNP) tightly bound to chromatin as well as cytoplasmic alpha-RNP are shown to possess strong and regulated endonuclease activity specific for mRNAs and hnRNAs. The enzymatic nature of this activity is confirmed, and the optimal conditions detected. This RNase activity is controlled by the action of a differentiating stimulus, dimethylsulfoxide, in human K562 cells. Small alpha-RNP involvement in the coordinated control of stability of pre-messenger RNA and messenger RNA molecules is suggested.
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PMID:The specific endoribonuclease activity of small nuclear and cytoplasmic alpha-RNPs. 1062 35

The distribution of ribosomes in mature human mast cells, a major granulated secretory cell, does not resemble that in other secretory cells, such as pancreatic acinar cells and plasma cells. By routine ultrastructural analysis, ribosomes in human mast cells are often close to, attached to, or even appear to be within secretory granules. To document better these relationships, we used multiple electron microscopic imaging methods, based on different principles, to define RNA, ribosome, and granule relationships in mature human mast cells. These methods included EDTA regressive staining, RNase digestion, immunogold labeling of ribonucleoproteins or uridine, direct binding or binding after ultrastructural in situ hybridization of various polyuridine probes to polyadenine in mRNA, and ultrastructural autoradiographic localization of [3H]-uridine incorporated into cultured human mast cells. These different labeling methods demonstrated ribosomes, RNA, U1SnRNP (a small nuclear RNP specific for alternative splicing of mRNA), mRNA, and uridine to be associated with secretory granules in human mast cells, implicating granules in a larger synthetic role in mast cell biology.
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PMID:RNA is closely associated with human mast cell secretory granules, suggesting a role(s) for granules in synthetic processes. 1065 81

RNP particles containing 20S prosomes (alpha RNP) isolated from human epidermoid carcinoma cell line A-431 are shown to posses strong and regulated endonuclease activity specific for high-molecular-weight RNA, particularly, specific mRNAs. Furthermore, alpha-RNP destabilize the 3'-untranslated regions of c-myc mRNA, creating a specific cleavage pattern. Cleavage point within Alu sequence in high-molecular-weight RNA has been localized by primer-extension method. This RNase activity is induced under the action of EGF. alpha-RNP involvement in the coordinated control of processing and stability of specific messenger RNA molecules is suggested. The endoribonuclease activity of alpha-RNP can represent a link between EGF signalling pathway and RNA processing and degradation.
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PMID:[Re-expression of various i-antigens in Dileptus anser after temporary transformation of serotype]. 1153 82


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