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  • Ryanodine receptor-ankyrin interaction regulates internal Ca2+ release in mouse T-lymphoma cells. 7629097

    In this study, we have identified and partially characterized a mouse T-lymphoma ryanodine receptor on a unique type of internal vesicle which bands at the relatively light density of 1.07 g/ml. Analysis of the binding of [3H]ryanodine to these internal vesicles reveals the presence of a single, low affinity binding site with a dissociation constant (Kd) of 200 nM. The second messenger, cyclic ADP-ribose, was found to increase the binding affinity of [3H]ryanodine to its vesicle receptor at least 5-fold (Kd approximately 40 nM). In addition, cADP-ribose appears to be a potent activator of internal Ca2+ release in T-lymphoma cells and is capable of overriding ryanodine-mediated inhibition of internal Ca2+ release. Immunoblot analyses using a monoclonal mouse antiryanodine receptor antibody indicate that mouse T-lymphoma cells contain a 500-kDa polypeptide similar to the ryanodine receptor found in skeletal muscle, cardiac muscle, and brain tissues. Double immunofluorescence staining and laser confocal microscopic analysis show that the ryanodine receptor is preferentially accumulated underneath surface receptor-capped structures. T-lymphoma ryanodine receptor was isolated (with an apparent sedimentation coefficient of 30 S) by extraction of the light density vesicles with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) in 1 M NaCl followed by sucrose gradient centrifugation. Further analysis indicates that specific, high affinity binding occurs between ankyrin and this 30 S lymphoma ryanodine receptor (Kd = 0.075 nM). Most importantly, the binding of ankyrin to the light density vesicles significantly blocks ryanodine binding and ryanodine-mediated inhibition of internal Ca2+ release. These findings suggest that the cytoskeleton plays a pivotal role in the regulation of ryanodine receptor-mediated internal Ca2+ release during lymphocyte activation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3086
    Nombre del producto:
    Anti-Ryanodine Receptor Antibody, clone RYR.1

  • Involvement of lysine residues in the gating of the ryanodine receptor/Ca2+-release channel of skeletal muscle sarcoplasmic reticulum. 9288920

    In this study, the modification of skeletal muscle ryanodine receptor (RyR)/Ca2+-release channel with 7-chloro-4-nitrobenzo-2-oxa-1,3,-diazole (Nbd-Cl) demonstrates that lysyl residues are involved in the channel gating. Nbd-Cl was found to have a dual effect: stimulation and inhibition of ryanodine binding and single channel activities. Nbd-Cl, in a time-dependent manner, first stimulated and subsequently inhibited ryanodine binding to both membrane-bound and purified RyR. Incubation of sacroplasmic reticulum membranes with Nbd-Cl for 5-20 s resulted in enhanced ryanodine-binding activity by 2-4-fold due, to an increased binding affinity by about tenfold, with no effect on the total binding sites (Bmax). However, under prolonged incubation (5-20 min), Nbd-Cl strongly inhibited ryanodine binding by decreasing the Bmax with no effect on the binding affinity. Similar effects of stimulation and inhibition by Nbd-Cl were obtained with single channel activity of RyR reconstituted into planar lipid bilayer. Nbd-Cl initially (within a few seconds) activated the channel to a highly open state, then (within a few minutes) inactivated it to the completely closed state. Nbd-Cl-modified protein, as assayed by ryanodine binding or single channel activities, was stable against thiolysis by dithiothreitol, suggesting Nbd-Cl modification of lysyl residues. Evidence from absorption and fluorescence excitation and emission spectra also demonstrated that lysyl residues in RyR were modified by Nbd-Cl. Spectrophotometric data were used to estimate a ratio of up to 1 mol Nbd bound/mol RyR (tetramer) and up to 4 mol Nbd bound per mol RyR (tetramer) for Nbd-Cl stimulated and inhibited RyR activities, respectively. The results clearly indicate the involvement of two classes of lysyl residues in RyR activity. Modification by Nbd-Cl of the fast-reacting group led to stimulation of ryanodine binding and single channel activities, while modification of the slow-reacting group resulted in inhibition of these activities. Thus, the involvement of lysine residues in the gating of the RyR channel is proposed.
    Tipo de documento:
    Referencia
    Referencia del producto:
    17-191
    Nombre del producto:
    MAP Kinase/Erk Assay Kit, non-radioactive

  • Functional SNP in the microRNA-367 binding site in the 3'UTR of the calcium channel ryanodine receptor gene 3 (RYR3) affects breast cancer risk and calcification. 21810988

    We have evaluated and provided evidence that the ryanodine receptor 3 gene (RYR3), which encodes a large protein that forms a calcium channel, is important for the growth, morphology, and migration of breast cancer cells. A putative binding site for microRNA-367 (miR-367) exists in the 3'UTR of RYR3, and a genetic variant, rs1044129 A→G, is present in this binding region. We confirmed that miR-367 regulates the expression of a reporter gene driven by the RYR3 3'UTR and that the regulation was affected by the RYR3 genotype. A thermodynamic model based on base pairing and the secondary structure of the RYR3 mRNA and miR-367 miRNA showed that miR-367 had a higher binding affinity for the A genotype than for the G genotype. The rs1044129 SNP was genotyped in 1,532 breast cancer cases and 1,600 healthy Chinese women. The results showed that compared with the AA genotype, G was a risk genotype for breast cancer development and was also associated with breast cancer calcification and poor survival. Thus, rs1044129 is a unique SNP that resides in a miRNA-gene regulatory loop that affects breast cancer risk, calcification, and survival.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB9082
    Nombre del producto:
    Anti-Ryanodine Receptor 3 Antibody

  • Identification and characterization of the high affinity [3H]ryanodine receptor of the junctional sarcoplasmic reticulum Ca2+ release channel. 2437119

    The high affinity ryanodine receptor of the Ca2+ release channel from junctional sarcoplasmic reticulum of rabbit skeletal muscle has been identified and characterized using monoclonal antibodies. Anti-ryanodine receptor monoclonal antibody XA7 specifically immunoprecipitated [3H]ryanodine-labeled receptor from digitonin-solubilized triads in a dose-dependent manner. [3H]Ryanodine binding to the immunoprecipitated receptor from unlabeled digitonin-solubilized triads was specific, Ca2+-dependent, stimulated by millimolar ATP, and inhibited by micromolar ruthenium red. Indirect immunoperoxidase staining of nitrocellulose blots of various skeletal muscle membrane fractions has demonstrated that anti-ryanodine receptor monoclonal antibody XA7 recognizes a high molecular weight protein (approximately 350,000 Da) which is enriched in isolated triads but absent from light sarcoplasmic reticulum vesicles and transverse tubular membrane vesicles. Thus, our results demonstrate that monoclonal antibodies to the approximately 350,000-Da junctional sarcoplasmic reticulum protein immunoprecipitated the ryanodine receptor with properties identical to those expected for the ryanodine receptor of the Ca2+ release channel.
    Tipo de documento:
    Referencia
    Referencia del producto:
    05-269

  • Physical coupling supports the local Ca2+ transfer between sarcoplasmic reticulum subdomains and the mitochondria in heart muscle. 18790739

    In many cell types, transfer of Ca(2+) released via ryanodine receptors (RyR) to the mitochondrial matrix is locally supported by high [Ca(2+)] microdomains at close contacts between the sarcoplasmic reticulum (SR) and mitochondria. Here we studied whether the close contacts were secured via direct physical coupling in cardiac muscle using isolated rat heart mitochondria (RHMs). "Immuno-organelle chemistry" revealed RyR2 and calsequestrin-positive SR particles associated with mitochondria in both crude and Percoll-purified "heavy" mitochondrial fractions (cRHM and pRHM), to a smaller extent in the latter one. Mitochondria-associated vesicles were also visualized by electron microscopy in the RHMs. Western blot analysis detected greatly reduced presence of SR markers (calsequestrin, SERCA2a, and phospholamban) in pRHM, suggesting that the mitochondria-associated particles represented a small subfraction of the SR. Fluorescence calcium imaging in rhod2-loaded cRHM revealed mitochondrial matrix [Ca(2+)] ([Ca(2+)](m)) responses to caffeine-induced Ca(2+) release that were prevented when thapsigargin was added to predeplete the SR or by mitochondrial Ca(2+) uptake inhibitors. Importantly, caffeine failed to increase [Ca(2+)] in the large volume of the incubation medium, suggesting that local Ca(2+) transfer between the SR particles and mitochondria mediated the [Ca(2+)](m) signal. Despite the substantially reduced SR presence, pRHM still displayed a caffeine-induced [Ca(2+)](m) rise comparable with the one recorded in cRHM. Thus, a relatively small fraction of the total SR is physically coupled and transfers Ca(2+) locally to the mitochondria in cardiac muscle. The transferred Ca(2+) stimulates dehydrogenase activity and affects mitochondrial membrane permeabilization, indicating the broad significance of the physical coupling in mitochondrial function.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • mAKAP and the ryanodine receptor are part of a multi-component signaling complex on the cardiomyocyte nuclear envelope. 11590243

    The physical association of regulatory enzymes and ion channels at relevant intracellular sites contributes to the diversity and specificity of second messenger-mediated signal transduction in cells. mAKAP is a scaffolding protein that targets the cAMP-dependent protein kinase A and phosphodiesterase type 4D3 to the nuclear envelope of differentiated cardiac myocytes. Here we present data that the mAKAP signaling complex also includes nuclear envelope-resident ryanodine receptors and protein phosphatase 2A. The ryanodine receptor is the major cardiac ion channel responsible for calcium-induced calcium release from intracellular calcium ion stores. As demonstrated by a combination of immunohistochemistry and tissue fractionation, mAKAP is targeted specifically to the nuclear envelope, whereas the ryanodine receptor is present at both the sarcoplasmic reticulum and nuclear envelope intracellular membrane compartments. At the nuclear envelope, a subset of cardiac ryanodine receptor is bound to mAKAP and via the association with mAKAP may be regulated by protein kinase A-mediated phosphorylation. By binding protein kinase A and ryanodine receptor, mAKAP may serve as the scaffold for a cAMP- and calcium ion-sensitive signaling complex.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-382

  • Ryanodine receptors are expressed in epidermal keratinocytes and associated with keratinocyte differentiation and epidermal permeability barrier homeostasis. 21881589

    Ryanodine receptors (RyRs) have an important role as calcium channels in the regulation of intracellular calcium levels in the nervous system and muscle. In the present study, we investigated the expression of RyR in human epidermis. Immunohistochemical studies and reverse transcription-PCR indicated the expression of RyR type 1, 2, and 3 proteins in epidermal keratinocytes. The expression level of each RyR subtype was higher in differentiating keratinocytes than in proliferative cells. We also demonstrated the functional expression of RyR by calcium imaging. In cultured human keratinocytes, application of the RyR agonist 4-chloro-m-cresol (CMC) induced elevation of the intracellular calcium concentration, and co-application of the RyR antagonist 1,1'-diheptyl-4,4'-bipyridinium dibromide (DHBP) blocked the elevation. Application of CMC accelerated keratinocyte differentiation in vitro. On the other hand, topical application of CMC after tape-stripping of hairless mouse skin delayed barrier recovery, whereas application of an RyR antagonist, dantrolene or DHBP, accelerated the barrier recovery. These results suggest that RyR expressed in epidermal keratinocytes is associated with both differentiation of keratinocytes and epidermal barrier homeostasis.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Phosphorylation-dependent regulation of ryanodine receptors: a novel role for leucine/isoleucine zippers. 11352932

    Ryanodine receptors (RyRs), intracellular calcium release channels required for cardiac and skeletal muscle contraction, are macromolecular complexes that include kinases and phosphatases. Phosphorylation/dephosphorylation plays a key role in regulating the function of many ion channels, including RyRs. However, the mechanism by which kinases and phosphatases are targeted to ion channels is not well understood. We have identified a novel mechanism involved in the formation of ion channel macromolecular complexes: kinase and phosphatase targeting proteins binding to ion channels via leucine/isoleucine zipper (LZ) motifs. Activation of kinases and phosphatases bound to RyR2 via LZs regulates phosphorylation of the channel, and disruption of kinase binding via LZ motifs prevents phosphorylation of RyR2. Elucidation of this new role for LZs in ion channel macromolecular complexes now permits: (a) rapid mapping of kinase and phosphatase targeting protein binding sites on ion channels; (b) predicting which kinases and phosphatases are likely to regulate a given ion channel; (c) rapid identification of novel kinase and phosphatase targeting proteins; and (d) tools for dissecting the role of kinases and phosphatases as modulators of ion channel function.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-852
    Nombre del producto:
    Anti-Spinophilin/Neurabin-II Antibody

  • The protective effect of dantrolene on ischemic neuronal cell death is associated with reduced expression of endoplasmic reticulum stress markers. 15921666

    The endoplasmic reticulum (ER) plays an important role in ischemic neuronal cell death. In order to determine the effect of dantrolene, a ryanodine receptor antagonist, on ER stress response and ischemic brain injury, we investigated changes in ER stress-related molecules, that is phosphorylated form of double-stranded RNA-activated protein kinase (PKR)-like ER kinase (p-PERK), phosphorylated form of eukaryotic initiation factor 2alpha (p-eIF2alpha), activating transcription factor-4 (ATF-4), and C/EBP-homologous protein (CHOP), as well as terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) in the peri-ischemic area and ischemic core region of rat brain after transient middle cerebral artery occlusion (MCAO). In contrast to the cases treated with vehicle, the infarct volume and TUNEL-positive cells were significantly reduced at 24 h of reperfusion by treatment with dantrolene. The immunoreactivities for p-PERK, p-eIF2alpha, ATF-4, and CHOP were increased at the ischemic peripheral region after MCAO, which were partially inhibited by dantrolene treatment. The present results suggest that dantrolene significantly decreased infarct volume and provided neuroprotective effect on rats after transient MCAO by reducing ER stress-mediated apoptotic signal pathway activation in the ischemic area.
    Tipo de documento:
    Referencia
    Referencia del producto:
    MAB3402
    Nombre del producto:
    Anti-Glial Fibrillary Acidic Protein Antibody, clone GA5

  • Diurnal and nutritional adjustments of intracellular Ca2+ release channels and Ca2+ ATPases associated with restricted feeding schedules in the rat liver. 23962056

    Intracellular calcium is a biochemical messenger that regulates part of the metabolic adaptations in the daily fed-fast cycle. The aim of this study was to characterize the 24-h variations of the liver ryanodine and IP3 receptors (RyR and IP3R) as well as of the endoplasmic-reticulum and plasma-membrane Ca2+-ATPases (SERCA and PMCA) in daytime restricted feeding protocol.A biochemical and immunohistochemical approach was implemented in this study: specific ligand-binding for RyR and IP3R, enzymatic activity (SERCA and PMCA), and protein levels and zonational hepatic-distribution were determined by immunoblot and immunohistochemistry respectively under conditions of fasting, feeding, and temporal food-restriction.Binding assays and immunoblots for IP3R1 and 2 showed a peak at the light/dark transition in the ad-libitum (AL) group, whereas in the restricted-feeding (RF) group the peak shifted towards the food-access time. In the case of RyR binding experiments, both AL and RF groups showed a modest elevation during the dark period, with the RF rats exhibiting increased binding in response to feeding. The AL group showed 24-h rhythmicity in SERCA level; in contrast, RF group showed a pronounced amplitude elevation and a peak phase-shift during the light-period in SERCA level and activity. The activity of PMCA was constant along day in both groups; PMCA1 levels showed a 24-h rhythmicity in the RF rats (with a peak in the light period), meanwhile PMCA4 protein levels showed rhythmicity in both groups. The fasted condition promoted an increase in IP3R binding and protein level; re-feeding increased the amount of RyR; neither the activity nor expression of SERCA and PMCA protein was affected by fasting-re-feeding conditions. Histochemical experiments showed that the distribution of the Ca2+-handling proteins, between periportal and pericentral zones of the liver, varied with the time of day and the feeding protocol.Our findings show that RF influences mainly the phase and amplitude of hepatic IP3R and SERCA rhythms as well as discrete zonational distribution for RyR, IP3Rs, SERCA, and PMCA within the liver acinus, suggesting that intracellular calcium dynamics could be part of the rheostatic adaptation of the liver due to diurnal meal entrainment/food entrained oscillator expression.
    Tipo de documento:
    Referencia
    Referencia del producto:
    AB9078
    Nombre del producto:
    Anti-Ryanodine Receptor 1 Antibody