Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A large fraction of the translationally repressed non-globin messenger RNA in duck erythroblasts is present in non-polyribosomal free mRNP structures which sediment in the 30-40-S range ('35 S'). In 0.5 M KCl, they form core complexes which show a pronounced peak at about 32 S containing mRNA and a discrete spherical RNP particle with a diameter of about 12 nm and the typical morphology of a prosome [H.-P. Schmid et al. (1984) EMBO J. 3, 29-34]. Buoyant density measurements and chromatography on oligo(dT)-cellulose indicate that this particle is bound to mRNA; it can be released from the mRNA by treatment of the free mRNP fraction with SDS. This prosome-like particle inhibits the translation of mRNA in vitro. It is composed primarily of multimers of a single 21-kDa protein and at least one species of RNA of about 80-100 nucleotides. It is resistant to dissociation by 2 M CS2SO4 and 1% SDS; the 21-kDa protein is not attacked by proteinase K unless the particle is extracted with phenol prior to treatment with the protease. The small RNA moiety of the particle hybridizes to the poly(A)-rich mRNA derived from the free mRNPs, as well as to polyribosomal mRNA. These data indicate that prosomes may serve to regulate mRNA translation; they show furthermore that prosome-like particles (about 600 kDa mass) may be built of up to 25 molecules of a single specific protein, rather than of the entire set of about 20 prosomal proteins previously identified.
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PMID:A new type of prosome-like particle, composed of small cytoplasmic RNA and multimers of a 21-kDa protein, inhibits protein synthesis in vitro. 369 21

The nature of the association of U1 RNA with rapidly sedimenting RNP structures in rat hepatoma nuclei was investigated. The effects of salt and proteinase K treatment on the stability of this 'bound' form of U1 RNA were studied using sucrose density gradient analyses. Quantitation of the amount of U1 RNA remaining associated with large structures after treatment was used to assess the relative contribution of protein-protein (and protein-RNA) versus RNA-RNA interactions. Forty-eight percent of the total nuclear U1 RNA released by sonication was found in a 'bound' form when the sonicate was centrifuged through gradients containing 50 mM NaCl. Fifty percent of this 'bound' U1 RNA remained associated with rapidly sedimenting RNPs when the NaCl concentration was raised to 500 mM. To assess the contribution of protein independent interactions, large RNPs were completely deproteinized and their RNA moieties were then recentrifuged on gradients. By this analysis, 27% of the U1 RNA originally 'bound' to hnRNPs was associated with rapidly sedimenting (greater than 30 S) RNA (at 50 mM NaCl) suggesting their association by RNA-RNA hydrogen bonds. When the concentration of NaCl was 500 mM, 31% of the U1 RNA was associated with large RNA. Hence, approximately 30% of the U1 RNA molecules originally 'bound' (or about 15% of the total nuclear U1 RNA) were found to be associated by RNA-RNA hydrogen bonds while the remainder of the binding of U1 RNP to hnRNP was by protein-protein and/or protein-RNA interactions.
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PMID:Interactions of U1 RNP with heterogeneous nuclear RNA in rat Novikoff hepatoma nuclei. 608 66

The interphase nucleolus in Allium porrum, as in many of the plant species studied so far, is highly heterogeneous in ultrastructure owing to the presence of coarse, contorted, thread-like structures, or nucleolonemata. Each nucleolonema appears to be sharply twisted and to give rise to a skein within the nucleolar mass. In order to characterize further these nucleolar components, a variety of cytochemical techniques were exploited. For that purpose, specimens were mostly fixed in 4% formaldehyde and stained in the block according to procedures known to reveal the presence of nucleic acids or proteins. Certain specimens were also digested with deoxyribonuclease, ribonuclease or proteinase K before staining. By staining with phosphotungstic acid or bismuth oxynitrate, the presence of a high concentration of proteins can be demonstrated within thin (0.15 micrometer), filamentous structures which are believed to correspond to the outer region of the nucleolonema. Such convoluted formations disappear upon sufficiently long extraction with proteinase K. Using Bernhard's regressive staining technique for chromatin, the distribution of this substance throughout the nucleolar mass was found to match closely that of the nucleolonemata as revealed by several other procedures. As a last test for investigating the cytochemical make-up of the nucleolus, blocks of tissues were stained with 3,3'-diaminobenzidine, a substance known to react specifically with nucleic acids. When such specimens are digested with ribonuclease for 1 h, there persist within the nucleolus, fibrillogranular zones the localization of which is highly reminiscent of that of the nucleolonemata. Combination of ribonuclease hydrolysis with subsequent treatment with proteinase K (30 min) induces the extraction of a large proportion of the nucleolar material, the persisting loose and rather evenly distributed fibrils exhibiting a diamter of 3-5 nm. The possibility is considered that these units may correspond to chromatin fibrils although they have most likely been displaced from their original localization during the extraction procedures. Our cytochemical data suggest that, in Allium porrum, the nucleolonema is approximately 0.3 micrometer in diameter and may consist of a central axis from which chromatin loops project radially. A possible interpretation for the presence of protein-rich, 0.1 micrometer-thick, annular structures throughout the nucleolonemal skein is that the newly synthesized RNP products are accumulated transiently at the extremities of these loops before migrating to the immediately adjacent granular nucleolar zones.
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PMID:An ultracytochemical study of nucleolar organization in meristematic plant cells (Allium porrum). 615 22

Chromatin depleted nuclei ('nuclear matrix') of Ehrlich ascites cells were characterized and fragmented by glycerol shot technique (particle fragmentation). The preparations reveal that 'nuclear matrix' is entirely composed of granules and fibres. Prominent size classes of granules are 10 to 20 nm and 25 to 40 nm, respectively. Most of the granules remain attached to fibres during the fragmentation process. The diameter of the fibres corresponds with double-stranded DNA visualized under identical conditions. The RNP-like nature of the particles is shown by their proteinase K/RNase sensitivity. Since the 'nuclear matrix' architecture becomes instable in high salt buffer after pretreatment with RNase which changes the RNP-particle-like material it must be inferred that the RNP/DNA interaction is a prerequisite for the high salt stability of the 'nuclear matrix' complex.
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PMID:Fragmentation of 'nuclear matrix' on a mica target. 661 72

During or immediately after transcription of chromatin the high molecular weight pre-mRNA is complexes with proteins and low molecular weight RNA (lmwRNA). In the presence of a cytosolic RNase inhibitor pre-mRNA-protein complexes, designated as polyparticles, can be isolated from rat liver nuclei. The polyparticles are characterized by a maximum of their sedimentation coefficient of around 90 S, a protein to RNA ratio of 4.1, and a density in CsCl of 1.4 g/cm3. A set of 6--10 basic proteins of molecular weights between 30 and 45 kd as well as a multitude of polypeptides of higher molecular weights is associated with the rapidly labeled, polydisperse, high molecular weight RNA and several lmwRNA species. In order to study the structure of these very complex nuclear RNP complexes, the polyparticles were incubated at various concentrations of sodium chloride, urea or proteinases of different specificities (trypsin, chymotrypsin, proteinase K), recentrifuged through a sucrose layer and analyzed with respect to their sedimentation behavior, their protein to RNA ratios and their protein- and RNA components. Rhe results of these experiments led us to the proposal of a structural model which is presented here.
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PMID:The structure of ribonucleoprotein particles from rat liver nuclei. 701 68