Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The morphological and certain metabolic effects of carbon tetrachloride intoxication were studied in the rat with emphasis on liver alterations. Morphological changes were investigated by histological and electron microscopical means. Functional changes were investigated using histochemical and amino acid incorporation, techniques. The liver constituents were examined chemically. Plasma volume alterations were measured using dye and homologous protein dilution techniques. The histological appearance of the liver of treated animals included cellular swelling, dispersal of the cytoplasmic basophilia, and necrosis. Electron micrographs showed an early (3 hours following carbon tetrachloride administration) and widespread dislocation of the ribonucleoprotein particles from the membranes of the rough endoplasmic reticulum, but no apparent alteration in the mitochondrial structure. Histochemical examination of two mitochondrial enzyme systems, alpha-ketoglutarate dehydrogenase and succinic dehydrogenase, revealed no alterations in activities until a later time (6 to 12 hours following carbon tetrachloride administration). ATPase showed a gross quantitative decrease in activity at 6 and 12 hours, but not earlier. There was a decreased amino acid incorporation into two liver-produced proteins, viz., albumin and fibrinogen. This decrease is not explicable on the basis of the inability of the liver to take up the amino acid, an altered dilution volume into which the amino acid or formed protein is placed, or an impaired capacity of the liver to excrete protein once formed. It is concluded that the decreased amino acid incorporation rate reflects depressed synthesis of protein by the liver. Other pathological changes in the liver, including necrosis, fatty change, and mitochondrial alterations may be dependent upon severe impairment of protein synthesis.
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PMID:An intracellular defect in protein synthesis induced by carbon tetrachloride. 1391 20

SEC-23 is a component of coat protein complex II (COPII)-coated vesicles involved in the endoplasmic reticulum-to-Golgi transport pathway of eukaryotes. During postembryonic life, Caenorhabditis elegans is surrounded by a collagenous exoskeleton termed the cuticle. From a screen for mutants defective in cuticle secretion, we identified and characterized a sec-23 mutant of C. elegans. By sequence homology, C. elegans has only the single sec-23 gene described herein. In addition to the cuticle secretion defect, mutants fail to complete embryonic morphogenesis. However, they progress through the earlier stages of embryogenesis, including gastrulation, and achieve substantial morphogenesis before death. We demonstrated a maternal component of SEC-23 function sufficient for progression through the earlier stages of embryogenesis and explaining the limited phenotype of the zygotic mutant. By RNA-mediated interference, we investigated the effects of perturbing COPII function during various postembryonic stages. During larval stages, major defects in cuticle synthesis and molting were observed. In the adult hermaphrodite, reduction of SEC-23 function by RNA-mediated interference caused a rapid onset of sterility, with defects in oogenesis including early maturation of the germline nuclei, probably a result of the observed loss of the GLP-1 receptor from the membrane surfaces adjacent to the developing germline nuclei.
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PMID:Loss of SEC-23 in Caenorhabditis elegans causes defects in oogenesis, morphogenesis, and extracellular matrix secretion. 1455 Dec 56

Ammodytoxin is a presynaptically neurotoxic (beta-neurotoxic) snake venom secretory phospholipase A(2) (sPLA(2)). We detected a 25 kDa protein which binds the toxin with very high affinity (R25) in porcine cerebral cortex. Here we show that R25 is an integral membrane protein with intracellular localisation. It is the first sPLA(2) receptor known to date that localises to intracellular membranes. Centrifugation on sucrose gradients was used to fractionate porcine cerebral cortex. The subcellular composition of the fractions was determined by following the distribution of organelle-specific markers. The distribution of R25 in the fractions matched the distribution of the mitochondrial marker succinate dehydrogenase, but not the markers for plasma membrane, lysosomes, endoplasmic reticulum, synaptic and secretory vesicles. R25 most likely resides in mitochondria, which are known to be targets for sPLA(2) neurotoxins in the nerve ending and are potentially implicated in the process of beta-neurotoxicity.
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PMID:R25 is an intracellular membrane receptor for a snake venom secretory phospholipase A(2). 1457 42

Modification by ubiquitin plays a major role in a broad array of cellular functions. Although reversal of this process, deubiquitination, likely represents an important regulatory step contributing to cellular homeostasis, functions of deubiquitination enzymes still remain poorly characterized. We have previously shown that the ubiquitin protease Ubp3p requires a co-factor, Bre5p, to specifically deubiquitinate the coat protein complex II (COPII) subunit Sec23p, which is involved in anterograde transport between endoplasmic reticulum and Golgi compartments. In the present report, we show that disruption of BRE5 gene also led to a defect in the retrograde transport from the Golgi to the endoplasmic reticulum. Further analysis indicate that the COPI subunit beta'-COP represents another substrate of the Ubp3p.Bre5p complex. All together, our results indicate that the Ubp3p.Bre5p deubiquitination complex co-regulates anterograde and retrograde transports between endoplasmic reticulum and Golgi compartments.
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PMID:Deubiquitination, a new player in Golgi to endoplasmic reticulum retrograde transport. 1459 9

Secretory proteins are transported from the endoplasmic reticulum (ER) in vesicles coated with coat protein complex II (COPII). To investigate the molecular mechanism of protein sorting into COPII vesicles, we have developed an in vitro budding reaction comprising purified coat proteins and cargo reconstituted proteolipsomes. Emp47p, a type-I membrane protein, is specifically required for the transport of an integral membrane protein, Emp46p, from the ER. Recombinant Emp46/47p proteins and the ER resident protein Ufe1p were reconstituted into liposomes whose composition resembles yeast ER membranes. When the proteoliposomes were mixed with COPII proteins and GMP-PNP, Emp46/47p, but not Ufe1p, were concentrated into COPII vesicles. We also show here that reconstituted Emp47p accelerates the GTP hydrolysis by Sar1p as stimulated by its GTPase-activating protein, Sec23/24p, both of which are components of the COPII coat. Furthermore, this GTP hydrolysis decreases the error of cargo sorting. We suggest that GTP hydrolysis by Sar1p promotes exclusion of improper proteins from COPII vesicles.
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PMID:Reconstitution of coat protein complex II (COPII) vesicle formation from cargo-reconstituted proteoliposomes reveals the potential role of GTP hydrolysis by Sar1p in protein sorting. 1462 16

Protein storage vacuoles (PSVs) are specialized vacuoles devoted to the accumulation of large amounts of protein in the storage tissues of plants. In this study, we investigated the presence of the storage vacuole and protein trafficking to the compartment in cells of tobacco (Nicotiana tabacum), common bean (Phaseolus vulgaris), and Arabidopsis leaf tissue. When we expressed phaseolin, the major storage protein of common bean, or an epitope-tagged version of alpha-tonoplast intrinsic protein (alpha-TIP, a tonoplast aquaporin of PSV), in protoplasts derived from leaf tissues, these proteins were targeted to a compartment ranging in size from 2 to 5 microm in all three plant species. Most Arabidopsis leaf cells have one of these organelles. In contrast, from one to five these organelles occurred in bean and tobacco leaf cells. Also, endogenous alpha-TIP is localized in a similar compartment in untransformed leaf cells of common bean and is colocalized with transiently expressed epitope-tagged alpha-TIP. In Arabidopsis, phaseolin contained N-glycans modified by Golgi enzymes and its traffic was sensitive to brefeldin A. However, trafficking of alpha-TIP was insensitive to brefeldin A treatment and was not affected by the dominant-negative mutant of AtRab1. In addition, a modified alpha-TIP with an insertion of an N-glycosylation site has the endoplasmic reticulum-type glycans. Finally, the early step of phaseolin traffic, from the endoplasmic reticulum to the Golgi complex, required the activity of the small GTPase Sar1p, a key component of coat protein complex II-coated vesicles, independent of the presence of the vacuolar sorting signal in phaseolin. Based on these results, we propose that the proteins we analyzed are targeted to the PSV or equivalent organelle in leaf cells and that proteins can be transported to the PSV by two different pathways, the Golgi-dependent and Golgi-independent pathways, depending on the individual cargo proteins.
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PMID:Identification of the protein storage vacuole and protein targeting to the vacuole in leaf cells of three plant species. 1473 78

Early effects of cadmium (Cd) on the structure and function of the kidney were studied in an experimental model using rats intoxicated with Cd at the levels of 5 and 50 mg Cd/l drinking water. The effect of Cd was evaluated histopathologically and biochemically. Damage to the cellular structures was assessed on the basis of histoenzymatic analyses of the activity and localization of indicator enzymes (succinate dehydrogenase, lactate dehydrogenase, glucose-6-phosphatase, Mg(2+)-dependent adenosine triphosphatase and acid phosphatase). The histochemical observations indicate that Cd causes damage to the organization and function of the nephron. Several structures, i.e. endoplasmic reticulum, mitochondrion, lysosome, cellular and intracellular membrane, as well as their biological functions, i.e. aerobic and anaerobic respiration, transport functions and biochemical processes taking place in the endoplasmic reticulum, were affected. The cytotoxic action of Cd occurs mainly in the tubules and partially also in the glomeruli. The results clearly indicate that Cd damages kidney structurally and functionally even at a relatively low level (5 mg/l) corresponding to human environmental exposure, and they confirm our previous hypothesis that the threshold for the kidney effects of Cd is less than 4.08+/-0.33 microg/g kidney wet weight and higher than 2.40+/-0.15 microg/g. The target for Cd action in the kidney is the tubules (proximal convoluted tubules and straight tubules), and disturbance in their function is the main toxic effect of Cd. Renal glomeruli are also injured, but only partially, whereas in other parts of the nephron the damage is slight. The results, together with observations reported in the first paper of the study, incline us to conclude that humans environmentally exposed to Cd are at risk of tubular damage.
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PMID:Changes in the structure and function of the kidney of rats chronically exposed to cadmium. II. Histoenzymatic studies. 1499 81

Like all members of the Na(+)/Cl(-)-dependent neurotransmitter transporter family, the rat gamma-aminobutyric acid transporter-1 (GAT1) is sorted and targeted to specialized domains of the cell surface. Here we identify two discontinuous signals in the carboxyl terminus of GAT1 that cooperate to drive surface expression. This conclusion is based on the following observations. Upon deletion of the last 37 amino acids, the resulting GAT1-Delta37 remained trapped in the endoplasmic reticulum. The presence of 10 additional residues (GAT1-Delta27) sufficed to support the interaction with the coat protein complex II component Sec24D; surface expression of GAT1-Delta27 reached 50% of the wild type level. Additional extensions up to the position -3 (GAT1-Delta3) did not further enhance surface expression. Thus the last three amino acids (AYI) comprise a second distal signal. The sequence AYI is reminiscent of a type II PDZ-binding motif; accordingly substituting Glu for Ile abrogated the effect of this motif. Neither the AYI motif nor the last 10 residues rescued the protein from intracellular retention when grafted onto GAT1-Delta37 and GAT1-Delta32; the AYI motif was dispensable for targeting of GAT1 to the growth cone of differentiating PC12 cells. We therefore conclude that the two segments act in a hierarchical manner such that the proximal motif ((569)VMI(571)) supports endoplasmic reticulum export of the protein and the distal AYI motif places GAT1 under the control of the exocyst.
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PMID:Two discontinuous segments in the carboxyl terminus are required for membrane targeting of the rat gamma-aminobutyric acid transporter-1 (GAT1). 1507 74

The elongated and polarized characteristics of neurons render targeting of receptors to the plasma membrane of distal axonal projections and dendritic branches a major sorting task. Although the majority of biosynthetic cargo synthesis, transport, and sorting are believed to occur in the soma, local membrane protein translation and sorting has been reported recently to take place in dendrites and axons. We investigated where endoplasmic reticulum (ER) export occurs in dendrites using an in vitro permeabilized neuron system that enables us to specifically control the assembly of ER export sites. We show that ER export sites are assembled regularly throughout the entire dendritic tree by the regulated sequential recruitment of Sar1 and COPII (coat protein complex II). Moreover, activation of metabotropic glutamate receptors leads to the recruitment of the NMDA receptor subunit NR1 to remodeled ER export sites. We propose that regulation of receptor assembly and export from the ER in dendrites plays an important role in modulating receptor surface expression and neuronal function.
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PMID:Endoplasmic reticulum export site formation and function in dendrites. 1508 57

In this study, we examine the role of the putative cargo receptor B cell-associated protein (Bap)29/31 in the export of MHC class I molecules out of the endoplasmic reticulum (ER). We show that Bap31 binds to two allotypes of mouse class I molecules, with the interaction initiated at the time of H chain association with beta(2)-microglobulin and maintained until the class I molecule has left the ER. We also show that Bap31 is part of the peptide-loading complex, although is not required for its formation. Bap31 binds not only to class I molecules, but can bind to tapasin in the absence of class I. Consistent with an important role in recruiting class I molecules to transport vesicles, we show that in the absence of Bap29/31, there is a loss of class I colocalization with mSec31 (p137), a component of mammalian coat protein complex II coats. This observation is also associated with a delay in class I traffic from ER to Golgi. Our results are consistent with the view that class I molecules are largely recruited to ER exit sites by Bap29/31, and that Bap29/31 is a cargo receptor for MHC class I molecules.
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PMID:Bap29/31 influences the intracellular traffic of MHC class I molecules. 1518 34


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