2,470,525 research outputs found
The involvement of ER calcium in abiotic stress tolerance
No full textCalcium application is known to reduce the deleterious effects of NaCl in many plant species. Ca2+ supplementation is thought to act by inhibiting ion channels that allow Na+ influx and by blocking Na+-induced K+ efflux. I generated transgenic Arabidopsis lines that constitutively express a low affinity, high capacity Calcium Binding Peptide (CBP) localized to the endoplasmic reticulum. Four independent transformed lines, two that also contained GFP and two that lacked it, were analyzed and contained up to 10% more total calcium than GFP control and wild-type plants. Each of these lines also showed increased K+ that was balanced by a decrease in Na+ accumulation. There were no significant changes in the relative amounts of other ions.
ER-CBP transgenic plants exhibited better salt and osmotic tolerance, increased survival in soil under intermittent drought conditions, longer root growth, higher chlorophyll content, and higher total seed production compared to GFP transgenic plants and control plants. One member of the CIPK (CBL-Interacting Protein Kinase) family, CIPK6, showed higher transcript levels in ER-CBP lines along with other drought-associated genes such as
DREB1a and rd29a, even under non-stress conditions. However, DREB2a transcript level was not affected by ER-CBP.
CIPK6 interacts with a Calcineurin B-Like Protein(s) (CBL) and was recently shown to interact with the C-terminus of the Arabidopsis Potassium Transporter1 (AKT1) protein. Using cipk6 null mutants, I showed that expression of both ER-CBP and CIPK6 was needed to achieve salt tolerance.
I used two methods, confocal ratio imaging of Indo-1 and cytoplasmically-expressed aequorin luminescence, to detect transient changes in [Ca2+]cyt in response to a salt stimulus.
There were no significant differences in [Ca2+]cyt measured by confocal ratio imaging between ER-CBP transgenic plants and control Arabidopsis plants in response to a short term salt treatment ( ~ 20 min). However, after three days incubation on 100 mM NaCl, ER-CBP lines had a higher steady state level of [Ca2+]cyt than wild type plants. Similarly, ER-CBP transgenic plants expressing aequorin in the cytoplasm did not show significant differences in Ca2+ spikes in response to 150 mM or 300 mM NaCl. After seedlings were grown on Ca2+ depleted media for 5 days, ER-CBP transgenic plants maintained Ca2+ peak heights similar to that seen before the low-calcium treatment, but control plants showed a decrease in Ca2+ spikes. This suggests that ER-CBP transgenic lines utilized extra ER Ca2+ stores under continual stress to maintain optimal Ca2+ levels in the cytoplasm.
Trehalose has been shown to play an important role in drought tolerance. It is one of the most studied osmoprotectants. ER-CBP transgenic lines exhibited increased Trehalose 6-phosphate synthase (TPS) and Trehalose-6-phosphate phosphatase (TPP) expression. Accordingly, the trehalose content of ER-CBP lines was significantly higher compared to control plants. These results strongly implicate ER calcium as being critical for sustained tolerance to drought and salt in Arabidopsis
Quan guo er tong zuo wen bi sai te deng zuo pin
No full text全國兒童作文比賽評判會編.Cover title.Quan guo er tong zuo wen bi sai ping pan hui bian
Sanatorium Moorbad Dachau, ER
No full textSANATORIUM MOORBAD DACHAU, ER
Sanatorium Moorbad Dachau, ER ( -
The isolated ER-Golgi intermediate compartment exhibits properties that are different from ER and cis-Golgi
No full textA procedure has been established in Vero cells for the isolation of an intermediate compartment involved in protein transport from the ER to the Golgi apparatus. The two-step subcellular fractionation procedure consists of Percoll followed by Metrizamide gradient centrifugation. Using the previously characterized p53 as a marker protein, the average enrichment factor of the intermediate compartment was 41. The purified fraction displayed a unique polypeptide pattern. It was largely separated from the rough ER proteins ribophorin I, ribophorin II, BIP, and protein disulfide isomerase, as well as from the putative cis-Golgi marker N-acetylglucosamine-1-phosphodiester-alpha-N-acetylglucosaminidase, the second of the two enzymes generating the lysosomal targeting signal mannose-6-phosphate. The first enzyme, N-acetylglucosaminylphosphotransferase, for which previous biochemical evidence had suggested both a pre- and a cis-Golgi localization in other cell types, cofractionated with the cis-Golgi rather than the intermediate compartment in Vero cells. The results suggest that the intermediate compartment defined by p53 has unique properties and does not exhibit typical features of rough ER and cis-Golgi
Targeting of protein ERGIC-53 to the ER/ERGIC/cis-Golgi recycling pathway
No full textERGIC-53 is a lectin-type membrane protein that continuously recycles between the ER, ER-Golgi intermediate compartment (ERGIC) and the cis-Golgi. To identify the targeting signals that mediate this recycling, N-glycosylated and myc-tagged variants of ERGIC-53 were constructed. By monitoring endoglycosidase H resistance, we measured the loss from the ER-ERGIC-cis-Golgi cycle of ERGIC-53. A domain exchange approach with the plasma membrane reporter protein CD4 showed that the transmembrane and the lumenal domains are not sufficient, while the cytoplasmic domain of ERGIC-53 is required and sufficient for pre-medial-Golgi localization. However, the ERGIC-53 cytoplasmic domain on CD4 lead to increased ER-staining by immunofluorescence microscopy indicating that this domain alone cannot provide for unbiased recycling through the ER-ERGIC-cis-Golgi compartments. Complete progress through the ER-ERGIC-cis-Golgi recycling pathway requires the cytoplasmic domain acting together with the lumenal domain of ERGIC-53. Dissection of the cytoplasmic domain revealed a COOH-terminal di-lysine ER-retrieval signal, KKFF, and an RSQQE targeting determinant adjacent to the transmembrane domain. Surprisingly, the two COOH-terminal phenylalanines influence the targeting. They reduce the ER-retrieval capacity of the di-lysine signal and modulate the RSQQE determinant
Er hu
No full text1. 古琴 / 吳文光, 1983 nov. 19 (c. 1 1/2 hr)-- 2. 二胡 / 余少華, nov. 2 1985.Detailed contents in vernacular field only.吳文光. 二胡 / 余少華.古琴: 吳文光, 卞趙如蘭 ; 二胡 : 余少華.Live recording."MASTER"--Spine label.Electronic reproduction from Rulan Chao Pian VHS collection.Spoken mainly in Chinese ; program name in English.Wu Wenguang. Er hu / Yu Shaohua.Gu qin: Wu Wenguang, Bian Zhao Rulan ; Er hu : Yu Shaohua
Drosophila REEP1 modulates ER morphology and ER stress
No full textDefects in endoplasmic reticulum (ER) membrane shaping and in lipid metabolism seem to be crucial mechanisms underlying Hereditary Spastic Paraplegia (HSP), a complex genetic disorder characterized by the axonal degeneration of corticospinal tracts. Here we report the analysis of a Drosophila melanogaster model of SPG31, an autosomal dominant form of HSP caused by mutations in the Receptor Expression Enhancing Protein1 gene (REEP1). REEP1 coordinates ER shaping within the tubular ER and confers resistance to ER stress in neurons, but the mechanism of this effect remains to be elucidated. In this work, we analyzed the effects of loss of D-REEP1 (REEPA) on the ER morphology, the Unfolded Protein Response (UPR), the locomotor activity and longevity. The absence of REEPA negatively affected longevity reducing lifespan as well as the locomotor activity. Moreover, REEPA mutant presented a larger proportion of apparent ER sheets, the up-regulation of ER-stress sensor Bip, the activation of Ire1 and ATF6 pathways, and a drastic reduction of the transcription level of two major enzymes involved in LDs biogenesis. The administration to REEPA mutant of naringenin, a flavanone known for its neuroprotective effects, rescued lifespan defect and ER homeostasis by decreasing UPR activation and enhancing LDs biogenesis, thus representing a promising strategy for the management of HSP symptoms
Carbohydrate- and conformation-dependent cargo capture for ER-exit
No full textSome secretory proteins leave the endoplasmic reticulum (ER) by a receptor-mediated cargo capture mechanism, but the signals required for the cargo-receptor interaction are largely unknown. Here, we describe a novel targeting motif that is composed of a high-mannose type oligosaccharide intimately associated with a surface-exposed peptide beta-hairpin loop. The motif accounts for lectin ERGIC-53-assisted ER-export of the lyososomal enzyme procathepsin Z. The second oligosaccharide chain of procathepsin Z exhibits no binding activity for ERGIC-53, illustrating the selective lectin properties of ERGIC-53. Our data suggest that the conformation-based motif is only present in fully folded procathepsin Z and that its recognition by ERGIC-53 reflects a quality control mechanism that acts complementary to the primary folding machinery in the ER. A similar oligosaccharide/beta-hairpin loop structure is present in cathepsin C, another cargo of ERGIC-53, suggesting the general nature of this ER-exit signal. To our knowledge this is the first documentation of an ER-exit signal in soluble cargo in conjunction with its decoding by a transport receptor
pcheng27/SAXS-ER: SAXS-ER
No full text<p>SAXS-ER (SAXS-oriented Ensemble Refinement of Flexible Biomolecules) is an iterative sampling method for selecting ensembles of large biomolecules that fit the experimental SAXS data.</p>
The formation and function of ER-endosome membrane contact sites
No full textRecent advances in membrane contact site (MCS) biology have revealed key roles for MCSs in inter-organellar exchange, the importance of which is becoming increasingly apparent. Roles for MCSs in many essential physiological processes including lipid transfer, calcium exchange, receptor tyrosine kinase signalling, lipid droplet formation, autophagosome formation, organelle dynamics and neurite outgrowth have been reported. The ER forms an extensive and dynamic network of MCSs with a diverse range of functionally distinct organelles. MCSs between the ER and endocytic pathway are particularly abundant, suggesting important physiological roles. Here, our current knowledge of the formation and function of ER contact sites with endocytic organelles from studies in mammalian systems is reviewed. Their relatively poorly defined molecular composition and recently identified functions are discussed. In addition, likely, but yet to be established, roles for these contacts in lipid transfer and calcium signalling are considered. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim Levine and Anant K. Menon
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