Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:O95477 (membrane-bound)
 29,236 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Early morphological changes in the ultrastructure of CL of ewes treated with prostaglandin F2alpha were examined in relation to luteal function as judged by plasma progesterone concentration. The luteolytic effect of prostaglandin F2alpha was confirmed, but there was little synchrony between morphological and functional luteolysis. Significant changes included a decrease in the amount of smooth endoplasmic reticulum, a change in the shape of mitochondria and a decrease in the number of membrane-bound granules. There was also an accumulation of lipids.
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PMID:Effect of prostaglandin F2 alpha on the ultrastructure and function of sheep corpora lutea. 116 13

We describe a typical case of prurigo nodularis, of 15 years' duration, in a middle-aged woman. Histological and electron microscopical examination of the skin lesions revealed distinct changes in the nerve tissue. There were groups of thickened nerve fibers that formed nodules with numerous Schwann cells. Some of the nerve bundles extended to the dermoepidermal junction. Electron microscopy showed very obvious lesions in the Schwann cells and axons. In the Schwann cells there was a lucent cytoplasm with few mitochondria, an absence of endoplasmic reticulum and a few irregular, membrane-bound vacuoles. While the mesaxons all appeared normal, the axons varied greatly in diameter; the small ones appeared normal and contained neurofibrils and neurotubules, whereas the large onew were empty. Every Schwann cell encircled a large number of axons. It may be assumed that the axon swelling is a nonspecific reaction to injury.
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PMID:Prurigo nodularis. Histological and electron microscopical study. 120 Jun 55

1. The glycosylation of hydroxylysine during the biosynthesis of procollagen by embryonic chick tendon and cartilage cells was examined. When free and membrane-bound ribosomes isolated from cells labelled for 4min with [(14)C]lysine were assayed for hydroxy[(14)C]lysine and hydroxy[(14)C]lysine glycosides, it was found that hydroxylation took place only on membrane-bound ribosomes and that some synthesis of galactosylhydroxy[(14)C]lysine and glucosylgalactosylhydroxy[(14)C]lysine had occurred on the nascent peptides. 2. Assays of subcellular fractions isolated from tendon and cartilage cells labelled for 2h with [(14)C]lysine demonstrated that the glycosylation of procollagen polypeptides began in the rough endoplasmic reticulum. (14)C-labelled polypeptides present in the smooth endoplasmic reticulum and Golgi fractions were glycosylated to extents almost identical with the respective secreted procollagens. 3. Assays specific for collagen galactosyltransferase and collagen glucosyltransferase are described, using as substrate chemically treated bovine anterior-lens-capsule collagen. 4. When homogenates were assayed for the collagen glycosyltransferase activities, addition of Triton X-100 (0.01%, w/v) was found to stimulate enzyme activities by up to 45%, suggesting that the enzymes were probably membrane-bound. 5. Assays of subcellular fractions obtained by differential centrifugation for collagen galactosyltransferase activity indicated the specific activity to be highest in the microsomal fractions. Similar results were obtained for collagen glucosyltransferase activity. 6. When submicrosomal fractions obtained by discontinuous-sucrose-density-gradient-centrifugation procedures were assayed for these enzymic activities, the collagen galactosyltransferase was found to be distributed in the approximate ratio 7:3 between rough and smooth endoplasmic reticulum of both cell types. Similar determinations of collagen glucosyltransferase indicated a distribution in the approximate ratio 3:2 between rough and smooth microsomal fractions. 7. Assays of subcellular fractions for the plasma-membrane marker 5'-nucleotidase revealed a distribution markedly different from the distributions obtained for the collagen glycosyltransferase. 8. The studies described here demonstrate that glycosylation occurs early in the intracellular processing of procollagen polypeptides rather than at the plasma membrane, as was previously suggested.
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PMID:Studies on the glycosylation of hydroxylysine residues during collagen biosynthesis and the subcellular localization of collagen galactosyltransferase and collagen glucosyltransferase in tendon and cartilage cells. 122 Jun 86

A simple reaction system was developed to examine the binding of polysomes to membranes of the endoplasmic reticulum and to investigate the fate of ribosomes and nascent chains during protein synthesis in vitro. The system conssited of Sephadex G-25 treated post-mitochondrial fraction prepared from rat liver (Sephadex-PM) as a source of membranes, and radioactive free polysomes prepared from another rat liver. The following results were obtained. 1. Nascent chains on free polysomes labeled in vivo were transferred to membranes in vitro. The process required protein synthesis. 2. This reaction occurred in two steps: a) Binding of the free polysomes to membranes in the absence of protein synthesis. b) Release of ribosomes, leaving nascent chains on the membranes, requiring protein syntehsis. 3. A portion of the ribosomes found on membranes in vivi (membrane-bound ribosomes) was also released from the membranes during incubation in vitro, leaving their nascent chains on the membranes. The significance of the transfer of nascent chains from free polysomes to membranes in vitro is discussed in the light of known polysome-membrane interaction in vivo.
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PMID:A polysome-membrane binding system from rat liver. I. Basic characterization of the binding system. 122 21

The present investigation was undertaken to discover whether in vivo inducers of autophagocytosis such as neutral red (0.40 mg/g body weight), cadmium chloride (0.15 mg/animal), vinblastine sulfate (7.5 mg/kg b.w.), and puromycin dihydrochloride (0.20 mg/g b.w.) are able to produce degranulation of rough surfaced endoplasmic reticulum (ER) of pancreatic acinar cells as we suggested earlier. Using a modified method of Blobel and Potter about 30% of the total ribosomes of untreated control pancreas were recovered in the free form, and 70% in the membrane-bound form. Cycloheximide (0.20 mg/g body weight) had no effect on this distribution of ribosomes, while neutral red, cadmium ions, vinblastine, and puromycin led to the presence of more free ribosomes: thus up to 70% of the total cytoplasmic ribosomes were recovered in the free form 30 to 60 min after treatments with the autophagic inducers. Pretreatments with cycloheximide prevented this shift and the distribution of ribosomes remained normal. On the basis of these and previous results we conclude that in pancreas an initial degranulation of the ER caused by these agents is a precondition of membrane transformation in autophagocytosis which is preventable by cycloheximide. Confirming the ultrastructural data of Longnecker et al. on rat pancreas, puromycin was shown to cause different forms of cellular injury including autophagocytosis. All forms of cellular injury were also prevented by pretreatment with cycloheximide in mouse pancreas.
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PMID:Attachment of ribosomes to endoplasmic membranes in mouse pancreas. Degranulation in vivo caused by the inducers of autophagocytosis neutral red, vinblastine, puromycin, and cadmium ions, and prevention by cycloheximide. 126 Sep 47

Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) of the rat brain, apparently identical with nitric oxide (NO) synthase, was demonstrated at the electron microscopic level by means of the tetrazolium salt 2-(2'-benzothiazolyl)-5-styryl-3-(4'-phthalhydrazidyl)tetrazolium chloride (BSPT). BSPT is a non-osmiophilic compound that yields an insoluble, osmiophilic, and lipophobic formazan on reduction. The reaction product was deposited sharply on membranes of the endoplasmic reticulum including the nuclear envelope. Other membrane structures were, as a rule, free of reaction product, likewise mitochondria. Occasionally, however, the outer membrane of mitochondria was labeled, and their contents displayed a homogeneous, medium electron density. The findings suggest that NADPH-d, i.e. neuronal NO synthase, is a predominantly membrane-bound enzyme, which is ubiquitously distributed in cells of brain tissue, but highly concentrated in nerve cells described as 'NADPH-d-positive' at the light microscopic level.
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PMID:Nitric oxide synthase in rat brain is predominantly located at neuronal endoplasmic reticulum: an electron microscopic demonstration of NADPH-diaphorase activity. 128 94

The distribution of (+)-[3H]SKF 10,047 binding sites and the distribution of the established plasma membrane, nuclear, mitochondrial and endoplasmic reticulum markers in subcellular fractions of rat liver have been studied. The distribution profile of (+)-[3H]SKF 10,047 binding sites coincided with that of NADPH-cytochrome c reductase, the endoplasmic reticulum marker. (+)-[3H]SKF 10,047 binding sites in rat liver are therefore suggested to be located on the endoplasmic reticulum membrane and to represent a membrane-bound enzyme.
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PMID:Subcellular distribution of (+)-[3H]SKF 10,047 binding sites in rat liver. 131 91

Addition of oleic acid to Krebs II cells induced a rapid incorporation of [3H]choline into phosphatidylcholine, since 500 microM of the fatty acid stimulated choline incorporation by 5-fold over the control after 5 min of incubation. In fact, a noticeable increase in phosphatidylcholine labelling could be monitored immediately after 1 min of cell incubation with [3H]choline, at which time 50% of cytosolic cytidylyltransferase activity (EC 2.7.7.15), the regulatory enzyme of phosphatidylcholine synthesis, was translocated on to membranes. Non-esterified [3H]oleic acid content was also increased in the same range of time in the particulate fraction. Subcellular fractionation indicated that endoplasmic reticulum was the unique binding site for cytidylyltransferase even after 1 min of incubation. Also, [3H]oleic acid accumulated mainly in the same internal membrane. Addition of exogenous albumin to cells prelabelled with [3H]oleic acid induced the release of 50% of membrane-bound cytidylyltransferase activity within 1 min, together with a decrease in unesterified oleic acid in the same membrane. Although total depletion of oleic acid was obtained, total release of membrane-bound cytidylyltransferase was not. The remaining minor pool of membrane-bound cytidylyltransferase was not affected by cell incubation with dibutyryl cyclic AMP, suggesting that this pool was neither regulated by fatty acid nor modulated by cyclic-AMP-dependent protein phosphorylation. Addition of [3H]oleic acid directly to an homogenate led to a less specific accumulation of the fatty acid in the endoplasmic reticulum, but cytidylyltransferase remained exclusively associated with this membrane. We concluded that in vivo translocation of cytidylyltransferase provoked by oleic acid concerns one specific pool of the enzyme distinct from the enzyme firmly bound to endoplasmic reticulum, but other factor(s) than fatty acid seem to be required to explain the specificity of endoplasmic reticulum for cytidylyltransferase binding.
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PMID:Reversible translocation of cytidylyltransferase between cytosol and endoplasmic reticulum occurs within minutes in whole cells. 131 24

Protein targeting to the endoplasmic reticulum (ER) in mammalian cells is catalysed by the signal recognition particle (SRP), which consists of six protein subunits and an RNA subunit. Saccharomyces cerevisiae SRP is a 16S particle, of which only two subunits have been identified: a protein subunit, SRP54p, which is homologous to the mammalian SRP54 subunit, and an RNA subunit, scR1 (ref. 3). The sec65-1 mutant yeast cells are temperature-sensitive for growth and defective in the translocation of several secreted and membrane-bound proteins. The DNA sequence of the SEC65 gene suggests that its product is related to mammalian SRP19 subunit and may have a similar function. Here we show that SEC65p is a subunit of the S. cerevisiae SRP and that it is required for the stable association of another subunit, SRP54p, with SRP. Overexpression of SRP54p suppresses both growth and protein translocation defects in sec65-1 mutant cells.
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PMID:SEC65 gene product is a subunit of the yeast signal recognition particle required for its integrity. 131 47

Large membrane-bound crystalline inclusions were seen on electron microscopic examination of the syncytiotrophoblast from the placenta of a HIV infected patient. The syncytium displayed abundant secretory granules (180-240 nm in diameter), with electron-dense centers (i.e., bull's eye granules or targetoid granules) which occasionally showed partial crystallization. Some crystals exhibited a periodicity of 9-10 nm. Electron-dense material was also seen in distended cisternae of the rough endoplasmic reticulum (RER). These granules correspond presumably to human placental lactogen (HPL) secretion, as seen on light microscopic immunoperoxidase stains. The morphological evidence is consistent with the idea that the crystals represent crystalline accumulation of secretory product (HPL), thus forming an analogy with crystal formation in other types of secretory cells. Ribosome-lamella complexes were seen in the many pericytes present in the capillaries of chorionic villi.
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PMID:Endocrine secretory granules and crystals in the syncytiotrophoblast. 131 21


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