Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.31.1 (micrococcal nuclease)
 2,818 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 593 nucleotide fragment of the 5' leader of encephalomyocarditis virus RNA (EMCV-RNA) was linked to the SP6 promoter and inserted upstream of the reporter gene chloramphenicol acetyltransferase (CAT). The presence of the 5'-UTR of EMCV-RNA in the RNA transcripts, made in vitro with the SP6 polymerase, resulted in a strong translational enhancement when tested in the micrococcal nuclease-treated reticulocyte lysate. The transcripts were equally active with or without a 5' methylated capstructure as expected, since EMCV-RNA is one of the mRNAs capable of internal initiation. We searched for a signal in the 5' leader that allows the 43S preinitiation complex to bind internally and localized a hairpin containing a unique nucleotide sequence, CUUUA, present in a domain conserved among cardio- and aphtoviral RNAs. Replacing this sequence into AGCU resulted in a 50% loss of translational activity. A second mutation involving a U-G change in the stem of that hairpin resulted in an almost complete loss of initiation.
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PMID:An initiation signal in the 5' untranslated leader sequence of encephalomyocarditis virus RNA. 216 87

Incubation of a SP6-transcribed human U2 RNA precursor molecule in a HeLa cell S100 fraction resulted in the formation of ribonucleoprotein complexes. In the presence of ATP, the particles that assembled had several properties of native U2 snRNP, including resistance to dissociation in Cs2SO4 gradients, their buoyant density, and pattern of digestion by micrococcal nuclease. These particles also reacted with Sm monoclonal antibody and a human autoantibody with specificity for the U2 snRNP-specific proteins A' and B", but not with antibodies for U1 snRNP-specific proteins. In contrast, the particles that formed in the absence of ATP did not have these properties. ATP analogs with non-hydrolyzable beta-gamma bonds did not substitute for ATP in U2 snRNP assembly. Additional experiments with a mutant U2 RNA confirmed that nucleotides 154-167 of U2 RNA are required for binding of the U2 snRNP-specific proteins but not of the "Sm" core proteins. Pseudouridine formation, a major post-transcriptional modification of U2 RNA, was enhanced under assembly permissive conditions.
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PMID:U2 small nuclear RNP assembly in vitro. 274 38

An SP6 RNA containing the adenovirus 5 L3 poly(A) site is processed efficiently in a HeLa cell nuclear extract to generate correct 3' termini. Accurate 3' processing has also been demonstrated for the adenovirus E2A and SV40 early poly(A) sites, although these are processed less efficiently than the L3 site. Efficient cleavage at the poly(A) site requires the presence of a 5'-cap structure, as well as the RNA sequence motifs previously shown to be necessary for 3' processing in vivo, suggesting the presence and action of the appropriate factors in the nuclear extract. Fractionation of the nuclear extract has revealed a requirement for at least two distinct factors for cleavage at the L3 poly(A) site. One of these factors appears to possess an RNA component due to its sensitivity to micrococcal nuclease. The activity of this fraction is also sensitive to alpha-Sm monoclonal antibody, indicating the presence of an snRNP essential for the cleavage reaction. Additional factors are required for the subsequent polyadenylation reaction, indicating the involvement of a multicomponent complex in the processing of an RNA at the poly(A) site.
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PMID:Multiple factors are required for specific RNA cleavage at a poly(A) addition site. 283 81