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)

We have developed a method for the isolation of a brain subcellular fraction enriched in both highly aggregated polyribosomes and cytoskeletal proteins. This method is based on gentle homogenization of brain tissue and low speed centrifugation. The mechanism of association of polyribosomes to cytoskeletal structures has been studied by in vitro treatment of this fraction with polyribosome-disaggregating agents. RNase and EDTA, while succeeding in completely disrupting them into monosomes or subunits, did not release them from cytoskeleton. Puromycin showed no noticeable effect.
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PMID:Isolation of hamster brain polyribosomes-cytoskeleton complexes. 249 51

A ribonuclease activity that has characteristics expected for an enzyme that catalyzes the regulated destabilization of serum protein-coding mRNAs following estrogen administration was previously identified on Xenopus liver polysomes. This enzyme activity is estrogen inducible and selectively degrades mRNAs (e.g., albumin, gamma-fibrinogen) that are unstable following estrogen administration to male frogs. This paper reports on the relationship between this enzyme activity and the association of 40S and 60S ribosomal subunits. Ribonuclease activity (as defined by the generation of a specific cleavage fragment from albumin RNA) is found in polysome fractions that contain the majority of the liver mRNA. This activity sediments on sucrose gradients with the large polysome complexes observed in liver of vitellogenic animals. EDTA treatment generates 40S and 60S ribosome subunits and a significant amount of 80S ribosome monomers. Under these conditions, polysomal ribonuclease activity is found both free in solution and with the 80S material. Puromycin treatment generates predominantly 40S and 60S ribosomal subunits. Polysomal ribonuclease activity is found only in solution following puromycin treatment. These data indicate that the Xenopus liver polysomal nuclease requires the association of both ribosomal subunits for complex formation with polysomes. The polysomal nuclease behaves as a basic protein on Mono Q chromatography, with the fractionated material retaining the same differential activity toward albumin versus ferritin mRNA.
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PMID:The nuclease that selectively degrades albumin mRNA in vitro associates with Xenopus liver polysomes through the 80S ribosome complex. 837 69

RNase MRP is a ribonucleoprotein endoribonuclease found in three cellular locations where distinct substrates are processed: the mitochondria, the nucleolus, and the cytoplasm. Cytoplasmic RNase MRP is the nucleolar enzyme that is transiently relocalized during mitosis. Nucleolar RNase MRP (NuMRP) was purified to homogeneity, and we extensively purified the mitochondrial RNase MRP (MtMRP) to a single RNA component identical to the NuMRP RNA. Although the protein components of the NuMRP were identified by mass spectrometry successfully, none of the known NuMRP proteins were found in the MtMRP preparation. Only trace amounts of the core NuMRP protein, Pop4, were detected in MtMRP by Western blot. In vitro activity of the two enzymes was compared. MtMRP cleaved only mitochondrial ORI5 substrate, while NuMRP cleaved all three substrates. However, the NuMRP enzyme cleaved the ORI5 substrate at sites different than the MtMRP enzyme. In addition, enzymatic differences in preferred ionic strength confirm these enzymes as distinct entities. Magnesium was found to be essential to both enzymes. We tested a number of reported inhibitors including puromycin, pentamidine, lithium, and pAp. Puromycin inhibition suggested that it binds directly to the MRP RNA, reaffirming the role of the RNA component in catalysis. In conclusion, our study confirms that the NuMRP and MtMRP enzymes are distinct entities with differing activities and protein components but a common RNA subunit, suggesting that the RNA must be playing a crucial role in catalytic activity.
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PMID:Comparison of mitochondrial and nucleolar RNase MRP reveals identical RNA components with distinct enzymatic activities and protein components. 2008 51

Many membrane proteins are cotranslationally integrated into the endoplasmic reticulum membrane via the protein-conducting channel, the so-called translocon. The hydrophobic transmembrane segment of the translocating nascent polypeptide chain stops at the translocon and then moves laterally into the membrane. Partitioning of the hydrophobic segment into the membrane is the primary determinant for membrane insertion. Here, we examined the behavior of a marginally hydrophobic segment at the translocon and found that its stop-translocation was greatly affected by the C-terminally attached ribosomes. The marginally hydrophobic segment first stops at the membrane and then moves into the lumen as long as the nascent chain is attached to translating ribosomes. When it is released from the ribosome by the termination codon, the marginally hydrophobic segment does not move. Puromycin or RNase treatment also suppressed movement. The movement was reversibly inhibited by high-salt conditions and irreversibly inhibited by ethylenediaminetetraacetic acid. There is an unstable state prior to the stable membrane insertion of the transmembrane segment. This characteristic state is maintained by the synthesizing ribosome.
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PMID:Stop-and-move of a marginally hydrophobic segment translocating across the endoplasmic reticulum membrane. 2374 84