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

Chromatin which was hydrodynamically sheared in a low ionic strength buffer lacking divalent cations (mu = 0.005) contains a heterogeneous set of DNP particles but no molecules of free DNA. The main finding is that a transference of sheared chromatin to 1-2 mM MgCl2 or to 0.1-0.2M NaCl results in the appearance of completely free DNA molecules. A salt-induced rearrangementof DNA-bound histones, but not a partial loss of them is responsible for the observed phenomenon. Formation of free DNA molecules is accompanied by aggregation of the majority of remaining DNP particles. Percentage of free DNA molecules in the chromatin which was sheared to an average DNA length of approx. 400 base pairs is increased from zero in the initial DNP sample to 8-9% in 1 mM MgCl2 and further to 30-31% of the total DNA in 0.30 M NaCl, 2 mM MgCl2. Free DNA molecules in the sheared chromatin are observed not only upon isopycnic banding of formaldehyde-fixed DNP in CsCl gradients but also in non-ionic Metrizamide gradients with either fixed or unfixed DNP samples. Process of free DNA formation is a reversible one; its direction and the equilibrium state depend in particular on the ionic conditions of the medium. Percentage of free DNA molecules in the sheared chromatin at a given ionic strength of solution is strongly decreased upon an increase of the average length of DNA in the DNP particles. Several lines of evidence suggest that free DNA molecules are formed in the sheared chromatin as a result of cooperative rearrangements of histones in salt-induced DNP aggregates. A dynamical model of chromosomal fiber is proposed on the basis of the present and earlier experimental data [1]. According to the model histones are arranged on DNA in clusters separated by stretches of free DNA. A salt-induced migration of histones along or between DNP fibers can result in unification of different clusters, thereby generating longer stretches of free DNA, the total amount of free DNA being approximately constant. Possible in vivo significance of such a dynamical structure is discussed.
Mol Biol (Mosk)
PMID:[Structure of chromosomal deoxyribonucleoproteins. VII. Free dna in preparation of fragmented chromatin]. 98 44

Administration of the antimalaria drug chloroquine increased the number of autophagic vacuoles (AVs) in the rat pancreas. Ultrastructural analysis showed that AVs contained segregated organelles such as mitochondria, zymogen granules, peroxisomes and small portions of cytoplasm. The maximum number of AVs was observed after 3 h of chloroquine treatment. The effect lasted for 12 h and almost disappeared after 16 h. The increase in AVs caused by chloroquine made it possible to isolate them in a discontinuous Metrizamide gradient with high purity. The proteolytic capacity of the AVs isolated after different chloroquine exposure times was measured after prelabeling pancreatic proteins with an injection of L-(1-14C)leucine 16 h before sacrifice. Protein degradation in isolated AVs increased during the first 6 h of chloroquine exposure and then returned to control values 16 h after the administration. In addition, the activities of two lysosomal enzymes, acid phosphatase and cathepsin B, increased in the AV-fractions following chloroquine treatment. It is concluded that the augmented proteolysis in the isolated AVs is due to a combination of increased substrate content and increased proteolytic lysosomal enzyme activities.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Proteolysis in isolated autophagic vacuoles from the rat pancreas. Effects of chloroquine administration. 168 22

The number of autophagic vacuoles in the proximal tubule cells of the rat kidney increased considerably after 3 h of vinblastine treatment. This increase was paralleled by stimulated proteolysis in an homogenate prepared from the cortex. We have taken advantage of this expansion in autophagic vacuoles in an effort to isolate these organelles from rat kidney cortex on a discontinuous Metrizamide gradient. Autophagic vacuoles have recently been purified from liver but not from other tissues. The purity of the isolated fraction was 95% of which 55% consisted of typical intact autophagic vacuoles containing sequestered organelles and 45% of other types of secondary lysosome. On plane section many of these displayed one or several intramatrical vesicles or flap like processes forming apparent vesicles at the pole of the organelles, which occasionally contained pinocytosed membranous material. These lysosomes were designated microautophagic vacuoles. It is suggested that the microautophagic vacuoles could be the morphological expression of uptake into lysosomes of small portions of cytosol. The isolated autophagic vacuole fraction was enriched in lysosomal enzymes (acid phosphatase and cathepsin D activities) and displayed high proteolytic rates, especially at acid pH.
Virchows Arch B Cell Pathol Incl Mol Pathol 1983
PMID:Isolation and characterization of autophagic vacuoles from rat kidney cortex. 614 61

Iron overload results in an accumulation of electron-dense iron-containing particles (IPs) such as ferritin and hemosiderin within the lysosomes of rat liver cells. In order to evaluate the effect or iron overload on lysosomal function, efforts were made to isolate lysosomes with different iron contents by means of ultracentrifugation in Percoll and Metrizamide gradients. Lysosomes isolated on the Percoll gradient were characterized ultrastructurally by a uniform matrix consisting mainly of IPs and these lysosomes contained a high iron concentration and showed a very low proteolytic activity. They may, therefore, constitute, or be equated, with a special type of residual bodies. They were also fragile, as judged by their significant release of enzymes during incubation in vitro. Lysosomes isolated in the Metrizamide gradient contained remnants of sequestered organelles and some IPs. These organelles displayed a somewhat impeded proteolytic activity compared with control lysosomes, as well as preserved membrane stability during incubation in vitro. We suggest that these may be precursors of the heavily iron-laden lysosomes recovered in the Percoll gradient. Our findings demonstrate that different populations of lysosomes exist in iron-overloaded rat liver cells, which show specific characteristics with regard to ultrastructural appearance, iron content and proteolytic activity. Differing iron contents is the most likely reason for their diverging densities and membrane integrities, whereas the difference in proteolytic activity could be a result of varying amounts of degradable substrate.
Virchows Arch B Cell Pathol Incl Mol Pathol 1984
PMID:Isolation of two lysosomal populations from iron-overloaded rat liver with different iron concentration and proteolytic activity. 615 Dec 88

A procedure has been developed for separating rat somatotroph and mammotroph secretory granules from other membranous organelles. The approach devised is a 6-step procedure involving filtration and equilibrium and rate density-gradient centrifugation in Metrizamide gradients of low ionic strength. The use of Metrizamide minimizes disruption and solubilization of the contents of these granules. The majority of the somatotroph and mammotroph granules can be isolated in a gradient fraction virtually free of any mitochondria, microsomes or other secretory granules.
Mol Cell Endocrinol 1980 Apr
PMID:Isolation of rat somatotroph and mammotroph secretory granules by equilibrium density centrifugation in a linear metrizamide gradient. 738 98

Bovine chromaffin secretory granules were purified by isopycnic Metrizamide gradient centrifugation and their Ca2+ sequestration pathways were characterized. The rate of Ca2+ sequestration at 37 degrees C was first order, with a maximal uptake of 26.9 +/- 0.46 (mean +/- S.D., n = 3) nmol Ca2+/mg protein and a first order rate constant (k) of 0.046 +/- 0.002 min-1. At 4 degrees C the rate of uptake was substantially attenuated, with only 2.47 +/- 0.2 (mean +/- S.D, n = 3) nmol Ca2+/mg protein sequestered in 60 min. Ca2+ sequestration was 93% inhibited by 180 mM NaCl [I50% of 78.7 +/- 9.3 mM NaCl (mean +/- S.D., n = 11)] but only slightly inhibited by KCl or MgCl2. Ca2+ sequestration was not stimulated by incubation with MgATP but was inhibited by 57% after incubation with 30 microM monensin. Ca2+ sequestration was dependent on extravesicular Ca2+ with half-maximal sequestration at pCa2+ 6.81 +/- 0.028 (mean +/- S.D., n = 3). Sequestered Ca2+ could be exchanged with external 45Ca2+, the exchange rate was first order (k of 0.042 +/- 0.004: mean +/- S.D., n = 3) and saturated at 27.7 +/- 1.1 nmol Ca2+/mg (mean +/- S.D., n = 3). The Ca2+/Ca2+ exchange system was totally inhibited by NaCl or KCl but only slightly by MgCl2. About 75% of sequestered 45Ca2+ could be released by incubation with NaCl, but only 8% was released by incubation with KCl. Half-maximal release of sequestered 45Ca2+ required 69.3 +/- 12.2 mM NaCl (mean +/- S.D., n = 3). The Na+-induced release of sequestered 45Ca2+ was rapid, t0.5 of 2.80 +/- 0.63 min (mean +/- S.D., n = 3) and inhibited at 4 degrees C. The concurrent incubation of chromaffin granules with 45Ca2+ and either annexin proteins V or VI resulted in attenuated uptake of 45Ca2+. These results suggest that Ca2+ uptake in adrenal chromaffin granules is regulated by Na+ and Ca2+ gradients and also possibly by annexins V and VI.
Mol Cell Biochem 1996 Feb 23
PMID:The uptake of calcium by isolated chromaffin granules of the adrenal medulla. 870 Jan 57

The Neurospora crassa vacuole, defined by its content of basic amino acids, polyphosphate, protease, phosphatases, and alpha-mannosidase, was purified to near homogeneity. The procedure depends upon homogenization of snail gut enzyme-digested cells in a buffer osmotically stabilized with 1 M sorbitol, differential centrifugation of the extract, and sucrose density gradient centrifugation of the organellar pellet. Isopycnic centrifugation of vacuoles in 2.25 M sorbitol-Metrizamide density gradients yielded a peak (density, 1.31 g/cm3) of vacuolar markers coincident with 32P-phospholipids, trichloroacetate-insoluble 14C, and trichloroacetate-soluble 14C. A trail of macromolecular markers in the lighter portions of the gradient reflected, at least in part, heterogeneity of the vacuoles. Almost no contamination by mitochondria or glyoxysomes was detected. Vacuoles were very heterogeneous in size as estimated by velocity sedimentation, but most were larger than mitochondria. Variations of the osmotic strength of the medium were found to alter the equilibrium density of vacuole preparations from 1.06 g/cm3 to over 1.3 g/cm3. This explains the great variation in density reported previously for the "vacuole," the "vesicle," and the "protease particle" of N. crassa, all of which appear to be the same entity.
Mol Cell Biol 1981 Sep
PMID:Purification of vacuoles from Neurospora crassa. 927 92