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)

Stimulation of lignin peroxidase production by exogenous phospholipids depends on the composition of the phospholipid fraction prepared by using the Nattermann process. The fraction composed mainly of negatively charged phospholipids (NAT 89) was the most efficient source for exoprotein secretion by Phanerochaete chrysosporium INA-12. The results of biochemical marker assays and ultrastructural morphology determination by electron microscopy were correlated. Activities of succinate dehydrogenase, a mitochondrial marker, and cytochrome c oxidoreductase, an endoplasmic reticulum (ER) marker, were increased 1.3- and 2.2-fold, respectively, in the presence of NAT 89. Electron microscopy observations suggested that the amount of mitochondria and ER in culture containing phospholipids was increased at the optimum day of lignin peroxidase production. Therefore, phospholipids enhanced energetic metabolism of strain INA-12 and markedly modified fungus physiology. Since ER is involved in enzyme synthesis, we suggest that its increased amount in mycelium cultured with NAT 89 is directly associated with the higher production of lignin peroxidase.
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PMID:Characterization of Peroxidase Secretion and Subcellular Organization of Phanerochaete chrysosporium INA-12 in the Presence of Various Soybean Phospholipid Fractions. 1634 81

The phospholipid transfer activity of cell extracts from 15 filamentous fungus strains grown on a medium containing phospholipids as the carbon source was measured by a fluorescence assay. This assay was based on the transfer of pyrene-labeled phosphatidylcholines forming the donor vesicles to acceptor vesicles composed of egg phosphatidylcholines. The highest phosphatidylcholine transfer activity was obtained with cell extracts from Aspergillus oryzae. The presence of exogenous phospholipids in the culture medium of A. oryzae was shown to increase markedly the activity of phospholipid transfer as well as the pool of exocellular proteins during the primary phase of growth. Modifications in the biochemical marker activities of cellular organelles were observed: succinate dehydrogenase, a mitochondrial marker; inosine diphosphatase, a Golgi system marker; and cytochrome c oxidoreductase, an endoplasmic reticulum marker, were increased 7.3-, 2-, and 22-fold, respectively, when A. oryzae was grown in the presence of phospholipids.
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PMID:Filamentous fungi with high cytosolic phospholipid transfer activity in the presence of exogenous phospholipid. 1634 88

Endomembranes of eukaryotic cells are dynamic structures that are in continuous communication through the activity of specialized cellular machineries, such as the coat protein complex II (COPII), which mediates cargo export from the endoplasmic reticulum (ER). COPII consists of the Sar1 GTPase, Sec23 and Sec24 (Sec23/24), where Sec23 is a Sar1-specific GTPase-activating protein and Sec24 functions in cargo selection, and Sec13 and Sec31 (Sec13/31), which has a structural role. Whereas recent results have shown that Sec23/24 and Sec13/31 can self-assemble to form COPII cage-like particles, we now show that Sec13/31 can self-assemble to form minimal cages in the absence of Sec23/24. We present a three-dimensional reconstruction of these Sec13/31 cages at 30 A resolution using cryo-electron microscopy and single particle analysis. These results reveal a novel cuboctahedron geometry with the potential to form a flexible lattice and to generate a diverse range of containers. Our data are consistent with a model for COPII coat complex assembly in which Sec23/24 has a non-structural role as a multivalent ligand localizing the self-assembly of Sec13/31 to form a cage lattice driving ER cargo export.
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PMID:Structure of the Sec13/31 COPII coat cage. 1640 55

Membrane traffic along the eukaryotic secretory pathway starts with the selective packing of biosynthetic cargo into nascent vesicles that are forming on the endoplasmic reticulum (ER). This process is mediated by the coat protein complex II (COPII) machinery, which at the minimum, comprises the Sar1 GTPase and the cytosolic protein complexes Sec23/Sec24 (Sec23/24) and Sec13/Sec31 (Sec13/31). While the components of the basic COPII machinery are highly conserved from yeast to human, it is now clearly evident that the overall process is under tighter spatial and temporal regulation in higher eukaryotes. Here we describe recombinant production in baculovirus-infected insect cells and subsequent purification to homogeneity of the mammalian Sec13/31 complex for biochemical and biophysical characterization.
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PMID:Recombinant production in baculovirus-infected insect cells and purification of the mammalian Sec13/Sec31 complex. 1641 57

The coat protein complex II (COPII) coat is responsible for direct capture of membrane cargo proteins and for the physical deformation of the endoplasmic reticulum (ER) membrane that drives the transport vesicle formation. The use of an in vitro reconstitution system comprising purified components is desirable for studies aimed at elucidating the role(s) of individual proteins in a specific biochemical reaction. To investigate the assembly-disassembly of COPII coats in a completely reconstituted reaction, we have developed a synthetic budding reaction involving purified coat proteins and cargo-reconstituted proteoliposomes. We describe here a fluorescence resonance energy transfer (FRET)-based method for monitoring the kinetics of COPII coat complex assembly and disassembly in cargo-reconstituted proteoliposomes. This assay allows comparison of the time course of the coat disassembly from the cargo as monitored by FRET signal with the time course of accompanying Sar1p GTP hydrolysis by tryptophan fluorescence.
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PMID:Reconstitution of cargo-dependent COPII coat assembly on proteoliposomes. 1641 60

Nicotine was shown to be associated with mature vacuoles isolated from protoplasts of Nicotiana rustica. The vacuolar preparations also contained high levels of acid phosphatase, ATPase, and approximately 30% of the soluble protoplastic protein. The contamination of the vacuolar isolate by chlorophyll, succinate dehydrogenase, and NADPH cytochrome c reductase (markers for chloroplasts, mitochondria, and endoplasmic reticulum) was low. The enzymic activity associated with the vacuoles was not due to the exogenously supplied digestive enzymes used in the preparation of the protoplast. The relatively easy isolation of tobacco vacuoles makes this an excellent system for biochemical investigations of the vacuole.
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PMID:Investigations of vacuoles isolated from tobacco: I. Quantitation of nicotine. 1666 Sep 18

Secretory proteins are exported from the endoplasmic reticulum (ER) in transport vesicles formed by the coat protein complex II (COPII). We detected Erv26p as an integral membrane protein that was efficiently packaged into COPII vesicles and cycled between the ER and Golgi compartments. The erv26Delta mutant displayed a selective secretory defect in which the pro-form of vacuolar alkaline phosphatase (pro-ALP) accumulated in the ER, whereas other secretory proteins were transported at wild-type rates. In vitro budding experiments demonstrated that Erv26p was directly required for packaging of pro-ALP into COPII vesicles. Moreover, Erv26p was detected in a specific complex with pro-ALP when immunoprecipitated from detergent-solublized ER membranes. Based on these observations, we propose that Erv26p serves as a transmembrane adaptor to link specific secretory cargo to the COPII coat. Because ALP is a type II integral membrane protein in yeast, these findings imply that an additional class of secretory cargo relies on adaptor proteins for efficient export from the ER.
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PMID:Erv26p directs pro-alkaline phosphatase into endoplasmic reticulum-derived coat protein complex II transport vesicles. 1695 51

The selective export of proteins and lipids from the endoplasmic reticulum (ER) is mediated by the coat protein complex II (COPII) that assembles onto the ER membrane. In higher eukaryotes, COPII proteins assemble at discrete sites on the membrane known as ER exit sites (ERES). Here, we identify Sec16 as the protein that defines ERES in mammalian cells. Sec16 localizes to ERES independent of Sec23/24 and Sec13/31. Overexpression, and to a lesser extent, small interfering RNA depletion of Sec16, both inhibit ER-to-Golgi transport suggesting that Sec16 is required in stoichiometric amounts. Sar1 activity is required to maintain the localization of Sec16 at discrete locations on the ER membrane, probably through preventing its dissociation. Our data suggest that Sar1-GTP-dependent assembly of Sec16 on the ER membrane forms an organized scaffold defining an ERES.
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PMID:Sec16 defines endoplasmic reticulum exit sites and is required for secretory cargo export in mammalian cells. 1700 10

In mammals, coat complex II (COPII)-coated transport vesicles deliver secretory cargo to vesicular tubular clusters (VTCs) that facilitate cargo sorting and transport to the Golgi. We documented in vitro tethering and SNARE-dependent homotypic fusion of endoplasmic reticulum-derived COPII transport vesicles to form larger cargo containers characteristic of VTCs ( Xu, D., and Hay, J. C. (2004) J. Cell Biol. 167, 997-1003). COPII vesicles thus appear to contain all necessary components for homotypic tethering and fusion, providing a pathway for de novo VTC biogenesis. Here we demonstrate that antibodies against the endoplasmic reticulum/Golgi SNARE Syntaxin 5 inhibit COPII vesicle homotypic tethering as well as fusion, implying an unanticipated role for SNAREs upstream of fusion. Inhibition of SNARE complex access and/or disassembly with dominant-negative alpha-soluble NSF attachment protein (SNAP) also inhibited tethering, implicating SNARE status as a critical determinant in COPII vesicle tethering. The tethering-defective vesicles generated in the presence of dominant-negative alpha-SNAP specifically lacked the Rab1 effectors p115 and GM130 but not other peripheral membrane proteins. Furthermore, Rab effectors, including p115, were shown to be required for homotypic COPII vesicle tethering. Thus, our results demonstrate a requirement for SNARE-dependent tether recruitment and function in COPII vesicle fusion. We anticipate that recruitment of tether molecules by an upstream SNARE signal ensures that tethering events are initiated only at focal sites containing appropriately poised fusion machinery.
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PMID:SNARE status regulates tether recruitment and function in homotypic COPII vesicle fusion. 1703 14

Sec24 of the COPII (coat protein complex II) vesicle coat mediates the selective export of membrane proteins from the endoplasmic reticulum (ER) in yeast. Human cells express four Sec24 isoforms, but their role is unknown. Here, we report the differential effects of Sec24 isoform-specific silencing on the transport of the membrane reporter protein ERGIC-53 (ER-Golgi intermediate compartment-53) carrying the cytosolic ER export signals di-phenylalanine, di-tyrosine, di-leucine, di-isoleucine, di-valine or terminal valine. Knockdown of single Sec24 isoforms showed dependence of di-leucine-mediated transport on Sec24A, but transport mediated by the other signals was not affected. By contrast, double knockdown of Sec24A with one of the other three Sec24 isoforms impaired all aromatic/hydrophobic signal-dependent transport. Double knockdown of Sec24B/C or Sec24B/D preferentially affected di-leucine-mediated transport, whereas knockdown of Sec24C/D affected di-isoleucine- and valine-mediated transport. The isoform-selective transport correlated with binding preferences of the signals for the corresponding isoforms in vitro. Thus, human Sec24 isoforms expand the repertoire of cargo for signal-mediated ER export, but are in part functionally redundant.
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PMID:Role of Sec24 isoforms in selective export of membrane proteins from the endoplasmic reticulum. 1725 61


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