TY - JOUR. T1 - Effects of Melittin on Molecular Dynamics and Ca-ATPase Activity in Sarcoplasmic Reticulum Membranes. T2 - Electron Paramagnetic Resonance. AU - Mahaney, James E.. AU - Thomas, David D. PY - 1991/7/1. Y1 - 1991/7/1. N2 - We have performed electron paramagnetic resonance (EPR) experiments on nitroxide spin labels incorporated into rabbit skeletal sarcoplasmic reticulum (SR), in order to investigate the physical and functional interactions between melittin, a small basic membrane-binding peptide, and the Ca-ATPase of SR. Melittin binding to SR substantially inhibits Ca2+-dependent ATPase activity at 25 °C, with half-maximal inhibition at 9 mol of melittin bound per mole of Ca-ATPase. Saturation transfer EPR (ST-EPR) of maleimide spin-labeled Ca-ATPase showed that melittin decreases the submillisecond rotational mobility of the enzyme, with a 4-fold increase in the effective rotational correlation time (τr) at a melittin/Ca-ATPase mole ratio of 10:1. This decreased rotational ...

TY - JOUR. T1 - Ca2+ signalling in cardiovascular disease. T2 - the role of the plasma membrane calcium pumps. AU - Cartwright, Elizabeth J. AU - Oceandy, Delvac. AU - Austin, Clare. AU - Neyses, Ludwig. PY - 2011/8. Y1 - 2011/8. N2 - The plasma membrane calcium ATPases (PMCA) are a family of genes which extrude Ca(2+) from the cell and are involved in the maintenance of intracellular free calcium levels and/or with Ca(2+) signalling, depending on the cell type. In the cardiovascular system, Ca(2+) is not only essential for contraction and relaxation but also has a vital role as a second messenger in signal transduction pathways. A complex array of mechanisms regulate intracellular free calcium levels in the heart and vasculature and a failure in these systems to maintain normal Ca(2+) homeostasis has been linked to both heart failure and hypertension. This article focuses on the functions of PMCA, in particular isoform 4 (PMCA4), in the heart and vasculature and the reported links between PMCAs ...

Paramecium, a unicellular ciliate, can be attracted by various chemical stimuli. Chemoattractants such as glutamate, folate, cAMP, and acetate activate different receptor mediated signal transduction pathways. The final event in these signal transductions is a hyperpolarization of membrane potential, which makes Paramecium swim smoothly and fast. There is evidence that the effecter of this hyperpolarization is the plasma membrane calcium ATPase (PMCA), that when activated, expels Ca2+ from the cell. In Paramecium three PMCA isoforms, named PMCA2, 3, and 4, have been cloned. PMCA2 is associated with lipid rafts, which is demonstrated by its resistance to cold detergent solubilization and distribution in sucrose density gradients in ultracentrifugation. PMCA3 and 4 are not associated with lipid rafts. On the cell surface, PMCAs are localized to the bases of cilia. Sterol-depletion by methyl-ß-cyclodextrin (MßCD) treatment disrupts the distribution of PMCA2 in sucrose density gradients and ciliary base

A dysfunctioning of Ca2+ pump ATPase in the sarcoplasmic reticulum in vascular smooth muscle has been proposed as a contributing factor for the development of genetic hypertension. In this study, we determined whether in vitro inhibition of the sarcoplasmic reticulum Ca2+ pump in vascular smooth muscle tissues and cultured cells isolated from aortas of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats would elicit the known alterations of contractile function and cell growth. We found the following common vascular effects of thapsigargin and cyclopiazonic acid, which are known to be selective inhibitors of sarcoplasmic reticulum Ca(2+)-ATPase in a number of tissues including smooth muscle: (1) Both sarcoplasmic reticulum Ca2+ pump inhibitors diminished agonist-induced transient contraction in Ca(2+)-free medium (ie, contraction due to intracellular release of Ca2+) and enhanced nifedipine-sensitive contraction on readmission of Ca2+ (ie, Ca2+ influx via L-type channels); and (2) ...

Angiogenesis, the de novo growth of blood vessels from pre-existing vessels, is an imperative, tightly-regulated process that underpins the expansion and refinement of the developing vascular network. However, in some pathological conditions, such as after a myocardial infarction, the vascular network can be destroyed necessitating the need for angiogenesis. Therefore stimulating angiogenesis could be therapeutically advantageous. Recently, plasma membrane calcium ATPase 4 (PMCA) has been established as a novel mediator of angiogenesis through its role in endothelial cell migration and tubule formation. In addition to PMCA4, both PMCA1 and PMCA2 are also expressed in human endothelial cells but their contribution to angiogenesis remains unknown. Therefore, we hypothesise that PMCA1 also modulates angiogenesis by altering endothelial cell behaviours.. Transient knockdown of PMCA1 was achieved in human umbilical vein endothelial cells (HUVECs) using siRNA (si-PMCA1) and confirmed with qPCR and ...

TY - JOUR. T1 - The role of ganglioside GM3 in the modulation of conformation and activity of sarcoplasmic reticulum CA2+-ATPase. AU - Yang, F. Y.. AU - Wang, L. H.. AU - Yang, X. Y.. AU - Tsui, Z. C.. AU - Tu, Yaping. PY - 1997/10. Y1 - 1997/10. N2 - Rabbit sarcoplasmic reticulum does contain trace amounts of gangliosides, and the main species is GM3. Incorporation of GM3 into the SR vesicles or addition of it to the soybean phospholipid used for reconstitution of proteoliposomes obviously increased ATP hydrolysis, as well as, Ca2+ uptake activity of sarcoplasmic reticulum Ca2+-ATPase. Conformation changes of Ca2+-ATPase induced by GM3 were also observed by circular dichroism, intrinsic fluorescence and fluorescence quenching measurements.. AB - Rabbit sarcoplasmic reticulum does contain trace amounts of gangliosides, and the main species is GM3. Incorporation of GM3 into the SR vesicles or addition of it to the soybean phospholipid used for reconstitution of proteoliposomes obviously increased ...

This magnesium-dependent enzyme catalyzes the hydrolysis of ATP coupled with the transport of calcium. Transports calcium ions from the cytosol into the sarcoplasmic/endoplasmic reticulum lumen. Contributes to calcium sequestration involved in muscular excitation/contraction.

The autoinhibition/activation of the PMCA (plasma membrane Ca2+-ATPase) involves conformational changes in the membrane region of the protein that affect the amount of lipids directly associated with the transmembrane domain. The lipid-protein-dependence of PMCA isoforms 2 and 4 expressed and obtained in purified form from Saccharomyces cerevisiae was investigated using the phosphatidylcholine analogue [125I]TID-PC/16 {l-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4-(trifluoromemyl-3H-diazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine}, which was incorporated into mixtures of dimyristoylphosphatidylcholine and the non-ionic detergent C12E10 [deca(ethylene glycol) dodecyl ether]. We found no differences between the recombinant PMCA4 and PMCA purified from erythrocytes (ePMCA). However, titration of the half-maximal activation by Ca2+/calmodulin of PMCA2 showed 30-fold higher affinity than PMCA4. PMCA2 exhibited a lower level of labelling in the autoinhibited conformation relative ...

It has been proposed that breakdown of the excitation-contraction coupling system plays a pivotal role in myocardial dysfunction during the course of acute ischemia. We tested this hypothesis by characterizing the function of the sarcoplasmic reticulum at pH 7.1 and 6.4 after 7.5, 15, and 30 minutes of canine normothermic global ischemia. At pH 7.1, whole heart homogenate sarcoplasmic reticulum demonstrated a 49% depression of oxalate-supported calcium uptake at 7.5 minutes of ischemia, which progressed to 85% at 30 minutes of ischemia. At pH 6.4, control homogenate calcium uptake rates were significantly depressed, accompanied by a further depression in the ischemic groups. Isolated sarcoplasmic reticulum calcium uptake mirrored the effects of the whole heart homogenate. Calcium-stimulated magnesium-dependent ATPase (calcium-ATPase) activity was significantly depressed by both ischemia and acidosis, with a decrease in the coupling ratio (mumol calcium/mumol ATP) at 15 and 30 minutes of ...

Calcium management differs in T and B lymphocytes. [Ca2+]i elevation in response to calcium ionophores is up to 10 times greater in T cells than B cells. There is no difference between them in ionophore uptake. T cells, but not B cells, possess a calcium-sensitive potassium channel which produces membrane hyperpolarization at [Ca2+]i above 200 nM. This alters T cell density providing a rapid and easy method of cell separation. In contrast, B cells depolarize when [Ca2+]i is increased. Isolated B cell membrane vesicle ATP-dependent calcium pump activity is higher than T cell vesicles. Membrane depolarization reduces the [Ca2+]i response to ionomycin, most dramatically in T cells because they are hyperpolarized by increased [Ca2+]i. The most likely basis of this behavior is an effect of membrane potential on lymphocyte membrane calcium pump activity. This mechanism provides an explanation of the inhibitory effect of membrane depolarization on T lymphocyte responses. ...

TY - JOUR. T1 - Characterization of the ATP-binding domain of the sarco(endo)plasmic reticulum Ca2+-ATPase. T2 - Probing nucleotide binding by multidimensional NMR. AU - Abu-Abed, Mona. AU - Mal, Tapas K.. AU - Kainosho, Masatsune. AU - MacLennan, David H.. AU - Ikura, Mitsuhiko. PY - 2002/1/29. Y1 - 2002/1/29. N2 - The skeletal muscle sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA1a) mediates muscle relaxation by pumping Ca2+ from the cytosol to the ER/SR lumen. In efforts aimed at understanding the structural basis for the conformational changes accompanying the reaction cycle catalyzed by SERCA1a, we have studied the ATP-binding domain of SERCA1a in both nucleotide-bound and -free forms by NMR. Limited proteolysis analyses guided us to express a 28 kDa stably folded fragment containing the nucleotide-binding domain of SERCA1a spanning residues Thr357-Leu600. ATP binding activity was demonstrated for this fragment by a FITC competition assay. A nearly complete backbone resonance assignment of ...

TY - JOUR. T1 - The regulation of ATPase-ATPase interactions in sarcoplasmic reticulum membrane. I. The effects of Ca2+, ATP, and inorganic phosphate.. AU - Dux, L.. AU - Martonosi, A.. PY - 1983/10/10. Y1 - 1983/10/10. N2 - Two-dimensional crystalline arrays of Ca2+-ATPase molecules develop after treatment of sarcoplasmic reticulum vesicles with Na3VO4 in calcium-free medium (Dux, L., and Martonosi, A. (1983) J. Biol. Chem. 258, 2599-2603). The formation of Ca2+-ATPase crystals is inhibited by Ca2+ (2 microM), or ATP (5 mM), but not by ADP, 5-adenylylimidodiphosphate, or adenylylmethylenediphosphonate. ATPase crystals did not form at 37 degrees C and exposure of preformed crystals to 37 degrees C for 1 h caused the disappearance of crystal lattice. Inorganic orthophosphate (1 mM at pH 6.0) promoted the formation of a distinct crystal form of Ca2+-ATPase, which was different from that produced by Na3VO4. These observations indicate that Ca2+, ATP, inorganic phosphate, pH, and temperature ...

In this study, we have analysed the relationship between Ca2+ pumps and Ins(1,4,5)P3-sensitive Ca2+ channels in myeloid cells. To study whether sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA)-type Ca2+-ATPases are responsible for Ca2+ uptake into Ins(1,4,5)P3-sensitive Ca2+ stores, we used the three structurally unrelated inhibitors thapsigargin, 2,5-di-t-butylhydroquinone and cyclopiazonic acid. In HL-60 cells, all three compounds precluded formation of the phosphorylated intermediate of SERCA-type Ca2+-ATPases. They also decreased, in parallel, ATP-dependent Ca2+ accumulation and the amount of Ins(1,4,5)P3-releasable Ca2+. Immunoblotting with subtype-directed antibodies demonstrated that HL-60 cells contain the Ca2+ pump SERCA2 (subtype b), and the Ca2+-release-channel type-1 Ins(1,4,5)P3 receptor. In subcellular fractionation studies, SERCA2 and type-1 Ins(1,4,5)P3 receptor co-purified. Immunofluorescence studies demonstrated that both type-1 Ins(1,4,5)P3 receptor and SERCA2 were ...

Unregulated increases in cellular Ca2+ homeostasis are a hallmark of pathophysiological conditions and a key trigger of cell death. Endothelial cells cultured under physiologic O2 conditions (5% O2) exhibit a reduced cytosolic Ca2+ response to stimulation. The mechanism for reduced plateau [Ca2+]i upon stimulation was due to increased sarco/endoplasmic reticulum Ca2+ ATPase (SERCA)-mediated reuptake rather than changes in Ca2+ influx capacity. Agonist-stimulated phosphorylation of the SERCA regulatory protein phospholamban was increased in cells cultured under 5% O2 Elevation of cytosolic and mitochondrial [Ca2+] and cell death after prolonged ionomycin treatment, as a model of Ca2+ overload, were lower when cells were cultured long-term under 5% compared with 18% O2 This protection was abolished by cotreatment with the SERCA inhibitor cyclopiazonic acid ...

The transfer of the terminal phosphate of ATP to a material from the sarcoplasmic reticulum of cardiac muscle which can be precipitated by trichloroacetic acid was studied, and the relationship of this biochemical event to active Ca2+ transport was examined. A component of the phosphoryl transfer reaction was stimulated specifically by Ca2+. Both the phosphorylation of the reticulum and the active sequestering of Ca2+ were proportional to the Ca2+ concentration between 10-7 and 10-5M. The time course of both phenomena was similar. These and other observations relating Ca2+-dependent phosphorylation of the membrane of the sarcoplasmic reticulum with the activesequestering of Ca2+ suggest that the phosphoryl transfer reaction may represent the formation of a carrier system which facilitates the inward flux of Ca2+ against a concentration gradient. Cyclic AMP, theophylline, or the combination of these two agents did not influence the rate or extent of the phosphorylation of the sarcoplasmic ...

The regulatory function of α1B-adrenoceptors in mammalian heart homeostasis is controversial. The objective of the present study was to characterize the expression/activity of key proteins implicated in cardiac calcium handling (Na+/K+-ATPase and Ca2+-ATPases) and growth (ERK1/2, JNK1/2 and p38) in mice with cardiac-selective overexpression of constitutively active mutant α1B-adrenoceptor (CAMα1B-AR), which present a mild cardiac hypertrophy phenotype. Immunoblot assays showed that myocardial plasma membrane Ca2+-ATPase (PMCA) expression was increased by 30% in CAMα1B-AR mice (N = 6, P , 0.05), although there was no change in sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2) expression. Moreover, total Ca2+-ATPase activity was not modified, but a significant increase in the activity of the thapsigargin-resistant (PMCA) to thapsigargin-sensitive (SERCA) ratio was detected. Neither Na+/K+-ATPase activity nor the expression of α1 and α2 subunit isoforms was changed in CAMα1B-AR mouse hearts. ...

Xu, K.Y.; Vandegaer, K.; Becker, L.C., 1999: The sarcoplasmic reticulum Ca(2+)-ATPase is depressed in stunned myocardium after ischemia-reperfusion, but remains functionally coupled to sarcoplasmic reticulum-bound glycolytic enzymes

Sigma-Aldrich offers abstracts and full-text articles by [Claire Harper, Laura Wootton, Francesco Michelangeli, Linda Lefièvre, Christopher Barratt, Stephen Publicover].

The structure, function and molecular biology of Ca2+ dependent regulatory proteins (particularly calmodulin) and the target proteins which they regulate is under study. One primary focus is the plasma membrane Ca2+-pumping ATPase (PMCA) in eucaryotes. Multiple isoforms of this enzyme are produced by alternative splicing of primary transcripts of four distinct genes. By artificial manipulation of expression through recombinant DNA methods, we have shown that products of one of these genes is required for proper cell adhesion, expression of a specific cell adhesion moleucle and for proper nerve growth factor action in a neuronal cell paradigm. We have also shown that the plasma membrane calcium pump is regulated by contact mediated tyrosine phosphorylation in both excitable cells and platelets. Studies are currently in progress using a variety of biochemical, immunological and molecular biological approaches to further elucidate the functions, expression, localization and physiological roles of ...

Evidence against inhibition of sarcoplasmic reticulum Ca2+-pump as mechanism of H2O2-induced contraction of rat aorta. Academic Article ...

Buy our Recombinant Human Phospholamban protein. Ab114227 is a protein fragment produced in Wheat germ and has been validated in WB, ELISA, SDS-PAGE. Abcam…

Identification of novel regulators of cardiac hypertrophy is key in understanding the mechanisms of heart failure. The plasma membrane calcium ATPase 4 (PMCA4)...

The sarco/endoplasmic reticulum Ca2+ -ATPase, SERCA2b or ATP2A2, is encoded by the ATP2A2 gene. Mutatioins give rise to Dariers disease; the spectrum of mutations have been related to patients phenotypes (Ahn et al., 2003; Godic et al. 2010). SERCA1 functions as a heat generator in mitochondria of brown adipose tissue (de Meis et al., 2006). It normally functions as a Ca2+:H+ antiporter (Karjalainen et al., 2007). Capsaicin converts SERCA to a Ca2+ non-transporting ATPase that generates heat, and is thus a natural drug that augments uncoupled SERCA, resulting in thermogenesis (Mahmmoud, 2008b). Oligomeric interactions of the N-terminus of sarcolipin with the Ca-ATPase have been documented (Autry et al., 2011), and these interactions also uncouple ATP hydrolysis from Ca2+ transport (Sahoo et al. 2015) resulting in thermogenesis. TMS 11, absent in SERCA1a and SERCA2a, functions in regulation (Gorski et al. 2012). The bovine SERCA has also been crystallized (2.9 Å resolution; Sacchetto et al., ...

Plasma Membrane Calcium ATPase 4, PMCA4, is the major Ca2+ efflux pump in murine sperm where its deletion leads to a severe loss of hyperactivated motility and to male infertility. Here I show that Pmca4 mRNA, 4a and 4b ...

In both cardiac and slow-twitch skeletal muscle sarcoplasmic reticulum (SR) there are several systems involved in the regulation of Ca2+-ATPase function. T

As a consequence of their vital importance, impaired activity of the ion pumps - such as by mutations or toxic compounds inhibiting them - is associated with diseases. Oppositely, the ion pumps can be targeted by medical drugs to alleviate ionic imbalances associated with disease, or they can be targeted in cancer cells or pathogenic organisms that then die. It is therefore very important to know how they work at an atomic level. To gain such insight, the research team used X-ray crystallography after having crystallized the calcium pump in a state that mimics the last step of the ATP cleaving reaction. In this state, a phosphoenzyme middle-product is cleaved to liberate free phosphate as the final product of the ATPase reaction, and after calcium has been released into the sarco-endoplasmic reticulum store. This step is closely mimicked by vanadate, where the phosphorus atom is replaced by vanadium and therefore produces a stable complex instead of a short-lived transition state. Like this a ...

Buy, download and read The Development of the Sarcoplasmic Reticulum ebook online in PDF format for iPhone, iPad, Android, Computer and Mobile readers. Author: Anthony Martonosi. ISBN: 9781482283624. Publisher: CRC Press. Sarcoplasmic reticulum is a form of endoplasmic reticulum found in large quantities in mature muscle cells. Anthony Martonosi presents general information about the development and function of the sar

DI-fusion, le Dépôt institutionnel numérique de lULB, est loutil de référencementde la production scientifique de lULB.Linterface de recherche DI-fusion permet de consulter les publications des chercheurs de lULB et les thèses qui y ont été défendues.

Mitsugumin 23 (MG23), also called TM protein 109 (Venturi et al., 2011). MG23 is a Ca2+ channel protein that is regulated by cytoplasmic Zn2+, and dysregulation of this ion channel plays a role in diastolic sarcoplasmic reticulum Ca2+ homeostasis, promoting leakage from the SR (Reilly-ODonnell et al. 2017 ...

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Introduction ATPase proteins are enzymes which are able to supply energy by cleaving ATP into ADP and phosphate. This energy can be used for…

Looking for online definition of Plasma membrane calcium pump isoform 4 in the Medical Dictionary? Plasma membrane calcium pump isoform 4 explanation free. What is Plasma membrane calcium pump isoform 4? Meaning of Plasma membrane calcium pump isoform 4 medical term. What does Plasma membrane calcium pump isoform 4 mean?

Looking for online definition of plasma membrane calcium pump in the Medical Dictionary? plasma membrane calcium pump explanation free. What is plasma membrane calcium pump? Meaning of plasma membrane calcium pump medical term. What does plasma membrane calcium pump mean?

HAILEY-HAILEY DISEASE. What are the aims of this leaflet?. This leaflet has been written to help you understand more about Hailey-Hailey disease. It tells you what it is, what causes it, what can be done about it, and where you can find out more about it.. What is Hailey-Hailey disease?. Hailey-Hailey disease is also known as familial benign chronic pemphigus, as originally described by the Hailey brothers. It is a rare inherited skin condition in which red scaly areas that can be itchy and sore, can lead to superficial blisters and eroded (broken) areas of the skin folds of the groin, armpits, neck and under the breasts. The condition flares intermittently and tends to come and go. Many patients are able to lead full and normal lives, with their condition being a nuisance rather than a serious problem. Some patients are more severely affected and experience more persistent painful raw areas of the skin with development of superficial blisters.. What causes Hailey-Hailey disease?. A small error ...

Ion pumps are integral membrane proteins responsible for transporting ions against concentration gradients across biological membranes. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), a member of the P-type ATPases family, transports two calcium ions per hydrolyzed ATP molecule via an alternating-access mechanism. High-resolution crystallographic structures provide invaluable insight on the structural mechanism of the ion pumping process. However, to understand the molecular details of how ATP hydrolysis is coupled to calcium transport, it is necessary to gain knowledge about the conformational transition pathways connecting the crystallographically resolved conformations. Large-scale transitions in SERCA occur at time-scales beyond the current reach of unbiased molecular dynamics simulations. Here, we overcome this challenge by employing the string method, which represents a transition pathway as a chainofstates linking two conformational endpoints. Using a multiscale methodology, we have ...

2015 by the American Thoracic Society. Autopsy specimens from human victims or experimental animals that die due to acute chlorine gas exposure present features of cardiovascular pathology. We demonstrate acute chlorine inhalation-induced reduction in heart rate and oxygen saturation in rats. Chlorine inhalation elevated chlorine reactants, such as chlorotyrosine and chloramine, in blood plasma. Using heart tissue and primary cardiomyocytes, we demonstrated that acute highconcentration chlorine exposure in vivo (500 ppm for 30 min) caused decreased total ATP content and loss of sarcoendoplasmic reticulum calcium ATPase (SERCA) activity. Loss of SERCA activity was attributed to chlorination of tyrosine residues and oxidation of an important cysteine residue, cysteine-674, in SERCA, as demonstrated by immunoblots and mass spectrometry. Using cardiomyocytes, we found that chlorine-induced cell death and damage to SERCA could be decreased by thiocyanate, an important biological antioxidant, and by ...

Tryptic peptides of Ca-ATPase in Et and E2 conformational states (Andersen, J. P., Jørgensen, P. L.,J. Membrane Biol. 88:187-198 (1985)) have been isolated by size exclusion high performance liquid chromatography in sodium dodecyl sulfate. This permitted unambiguous localization of a conformational sensitive tryptic split at Arg 198 by N-terminal amino acid sequence analysis. Other splits at Arg 505 and at Arg 819-Lys 825 were insensitive to E1-E2 transitions. Tryptic cleavage of Ca-ATPase after phosphorylation by inorganic phosphate showed that this enzyme form has a conformation similar to that of the vanadate-bound E2 state, both in membranous and in soluble monomeric Ca-ATPase. Hydrophobic labeling of Ca-ATPase in sarcoplasmic reticulum vesicles with the photoactivable reagent trifluoromethyl-[125I]iodophenyl-diazirine indicated that E2 and E2V states are more exposed to the membrane phase than E1 and E1P (Ca2+-occluded) states. The preferetial hydrophobic labeling in E2 forms was found to be

Hailey-Hailey disease is a rare genetic condition that is characterized by blistering or scaling of the skin, usually over the neck, skin folds, armpits and genitals. The condition usually becomes apparent between the ages of 15 and 40 years, although symptoms may develop at any age.

The sarco(endo)plasmic reticulum calcium ATPase (SERCA) family of proteins function as calcium pumps in the endoplasmic reticulum (ER) and sarcoplasmic reticulum (SR) membranes. SERCA1a is found exclusively in fast-twitch muscle cells and mediates muscle relaxation by pumping calcium back into the SR after calcium has been released into the cytoplasm to elicit muscle contraction. The mechanism which allows SR biogenesis is not known, but SR membrane is believed to bud from the ER. One hypothesis is that SERCA1a proteins play a significant role in SR biogenesis in fast-twitch skeletal muscle due the proteins large size and clustering into large arrays in the SR membrane. SERCA1a arrays could recruit lipids which would allow for a large increase in membrane size that could result in the formation of the SR. Also, SERCA1a is highly expressed during the early stages of myogenesis, at the same time the first emergence of the SR is observed. It is known that SERCA1a contains ER targeting information ...

In previous efforts to characterize sarcoplasmic reticulum function in human muscles, it has not been possible to distinguish the relative contributions of fast-twitch and slow-twitch fibers. In this study, we have used light scattering and 45Ca to monitor Ca accumulation by the sarcoplasmic reticulum of isolated, chemically skinned human muscle fibers in the presence and absence of oxalate. Oxalate (5 mM) increased the capacity for Ca accumulation by a factor of 35 and made it possible to assess both rate of Ca uptake and relative sarcoplasmic reticulum volume in individual fibers. At a fixed ionized Ca concentration, the rate and maximal capacity (an index of sarcoplasmic reticulum volume) both varied over a wide range, but fibers fell into two distinct groups (fast and slow). Between the two groups, there was a 2- to 2.5-fold difference in oxalate-supported Ca uptake rates, but no difference in average sarcoplasmic reticulum volumes. Intrinsic differences in sarcoplasmic reticulum function ...

In muscle cells, the excitation-contraction cycle is triggered by an increase in the concentration of free cytoplasmic Ca(2+). The Ca(2+)-ATPase present in the membrane of the sarcoplasmic reticulum (SR) pumps Ca(2+) from the cytosol into this intracellular compartment, thus promoting muscle relaxation. The microsomal fraction derived from the longitudinal smooth muscle of the body wall from the sea cucumber Ludwigothurea grisea retains a membrane-bound Ca(2+)-ATPase that is able to transport Ca(2+) mediated by ATP hydrolysis. Immunological analyses reveal that monoclonal antibodies against sarco-endoplasmic reticulum Ca(2+)-ATPase (SERCA1 and SERCA2a) cross-react with a 110 kDa band, indicating that the sea cucumber Ca(2+)-ATPase is a SERCA-type ATPase. Like the mammalian Ca(2+)-ATPase isoforms so far described, the enzyme also shows a high affinity for Ca(2+) and ATP, has an optimum pH of approximately 7.0 and is sensitive to thapsigargin and cyclopiazonic acid, specific inhibitors of the ...

The major finding of the present study is that type 2 diabetes mellitus is associated with the cleavage of platelet PECAM-1 through a mechanism involving the tyrosine nitration of SERCA-2, an increase in [Ca2+]i, and the activation of the Ca2+-dependent protease μ-calpain. Moreover, treating subjects with type 2 diabetes mellitus with the PPAR-γ agonist rosiglitazone successfully reversed many of these changes and restored platelet [Ca2+]i, calpain activity, and PECAM-1 to levels comparable to those detected in nondiabetic subjects. From these results, it is clear that megakaryocytes/platelets are an additional cellular target for PPAR-γ agonists.. Intracellular Ca2+ homeostasis in platelets from patients with type 2 diabetes mellitus is reported to be altered, leading to an increased adhesiveness and spontaneous aggregation. One factor that contributes to the disturbed platelet [Ca2+]i in diabetic subjects is a marked reduction in Ca2+-ATPase activity.3,4 Although human platelets coexpress ...

TY - JOUR. T1 - Transmembrane Ca2+ gradient-mediated change of fluidity in the inner layer of phospholipids modulates Ca2+-ATPase of sarcoplasmic reticulum. AU - Tu, Yaping. AU - Xu, H.. AU - Yang, F. Y.. PY - 1994. Y1 - 1994. N2 - Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without transmembrane Ca2+ gradient have been prepared. Different fluorescence probes (DPH, TMA-DPH and n-AS), were used to determine the effect of transmembrane Ca2+ gradient on the lipid fluidity both in outer and inner layer of Ca2+-ATPase-containing SR vesicles. The results showed that transmembrane Ca2+ gradient could significantly decrease the fluidity of the inner layer of SR membrane, while no obvious change was monitored in the outer layer. This may be deduced that Ca2+-ATPase might be modulated mainly by the transmembrane Ca2+ gradient-mediated alteration of physical state of phospholipid in the inner layer of SR membrane.. AB - Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without ...

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Localized, transient elevations in cytosolic Ca2+, known as Ca2+ sparks, caused by Ca2+ release from sarcoplasmic reticulum, are thought to trigger the opening of large conductance Ca2+-activated potassium channels in the plasma membrane resulting in spontaneous transient outward currents (STOCs) in smooth muscle cells. But the precise relationships between Ca2+ concentration within the sarcoplasmic reticulum and a Ca2+ spark and that between a Ca2+ spark and a STOC are not well defined or fully understood. To address these problems, we have employed two approaches using single patch-clamped smooth muscle cells freshly dissociated from toad stomach: a high speed, wide-field imaging system to simultaneously record Ca2+ sparks and STOCs, and a method to simultaneously measure free global Ca2+ concentration in the sarcoplasmic reticulum ([Ca2+]SR) and in the cytosol ([Ca2+]CYTO) along with STOCs. At a holding potential of 0 mV, cells displayed Ca2+ sparks and STOCs. Ca2+ sparks were associated with STOCs;

Buy anti-ATP2A2 antibody, Mouse ATPase 2, Ca2+ Transporting, Sarcoplasmic Endoplasmic Reticulum Monoclonal Antibody (Clone 6D141)-NP_999030.1 (MBS604309) product datasheet at MyBioSource, Primary Antibodies. Application: Western Blot (WB), Immunohistochemistry (IHC), Immunocytochemistry (ICC)

The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) pumps are approximately 100 kDa transmembranous proteins that catalyze the ATP-dependent transport of cytosolic Ca2+ [Ca2+]i into the sarcoplasmic reticulum (SR), thereby maintaining low concentrations of resting [Ca2+]i. Reactive free- and non-radical oxygen and nitrogen species regulate SERCA function. Additionally, free radicals can oxidize lipids producing bioactive lipid-peroxidation end-products which are capable of modifying membranous proteins, resulting in protein inactivation. Here, in order to characterize the effect of 4-HNE, a lipid-peroxidation end-product, on SERCA structure and function, mouse WG and LV tissues were treated with 4-HNE and subsequently assayed for maximal Ca2+-dependent SERCA activity and SERCA post-translational structural modifications. Ca2+-dependent, maximal SERCA activity assays demonstrate a dose-dependent functional impairment of the SERCA pumps following 4-HNE treatment; interestingly, western blotting ...

Strehler EE and Zacharias DA. Department of Biochemistry and Molecular Biology, Mayo Graduate School, Mayo Clinic/Foundation, Rochester, Minnesota, USA. [email protected]. Calcium pumps of the plasma membrane (also known as plasma membrane Ca(2+)-ATPases or PMCAs) are responsible for the expulsion of Ca(2+) from the cytosol of all eukaryotic cells. Together with Na(+)/Ca(2+) exchangers, they are the major plasma membrane transport system responsible for the long-term regulation of the resting intracellular Ca(2+) concentration. Like the Ca(2+) pumps of the sarco/endoplasmic reticulum (SERCAs), which pump Ca(2+) from the cytosol into the endoplasmic reticulum, the PMCAs belong to the family of P-type primary ion transport ATPases characterized by the formation of an aspartyl phosphate intermediate during the reaction cycle. Mammalian PMCAs are encoded by four separate genes, and additional isoform variants are generated via alternative RNA splicing of the primary gene transcripts. The ...

Recent studies have been directed towards the potential therapeutic value of improving the sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA) function in the failing myocardium. Overexpression of SERCA pump or inhibiting the function of phospholamban (PLB) has been shown to improve the cardiac function in failing myocardium. Towards this goal, we enhanced the SERCA pump activity in both atria and ventricle by ablating its key regulators, PLB and sarcolipin (SLN). The homozygous double knockout (dKO) pups were delivered in Mendelian ratio and reached adulthood without any visible abnormalities. However, these mice develop cardiac hypertrophy. The heart weight to body weight ratio significantly increased in 3- 4 months old dKO mice (WT-3.08±0.11 vs. dKO-4.14±0.14) and is associated with enlargement of myocytes (WT-117±8 μm2 vs. dKO-166±10 μm2). Ablation of PLB and SLN did not affect the expression of major Ca2+ handling proteins including SERCA2a, calsequestrin, L-type Ca2+ channel and ...

The steady-state ATPase activity of sarcoplasmic-reticulum (Ca(2+)-Mg2+)-ATPase is inhibited by thapsigargin at a molar ratio of 1:1, with a dissociation constant for thapsigargin estimated to be in the sub-nanomolar range. In the presence of thapsigargin, only a single Ca2+ ion binds to the ATPase. Similarly, addition of thapsigargin to the ATPase incubated in the presence of Ca2+ results in the release of one of the two originally bound Ca2+ ions. As monitored by the fluorescence of nitrobenzo-2-oxa-1,3-diazole-labelled ATPase, thapsigargin appears to shift the transition between E1 and E2 conformations towards E2. Addition of thapsigargin prevents phosphorylation of the ATPase by P(i) and results in a very low steady-state level of phosphorylation of the ATPase by ATP, as observed previously for nonylphenol. ...

Pflügers Archiv - European Journal of Physiology. Stromal interaction molecule 1 (STIM1) regulates sarcoplasmic/endoplasmic reticulum Ca 2+ -ATPase 1a (SERCA1a) in skeletal muscle Keon Jin Lee 1 , Changdo Hyun 1 , Jin Seok Woo 1 , Chang Sik Park 2 , Do Han Kim 2 , Eun Hui Lee 1,* Slideshow...

We describe for the first time that SERCA1 truncated proteins encoded by new splice variants (S1T) of the SERCA1 gene. S1T are characterized by exon 4 and/or exon 11 splicing, leading to COOH-terminally truncated proteins with deletion of transmembrane segments M2 and/or M5 to M10 including six out of seven transmembrane calcium-binding residues (Toyoshima et al. 2000). Consistent with the analysis of previously reported SERCA1 mutants (MacLennan et al. 1998), they are unable to pump calcium. We show that S1T protein overexpression is associated with a reduction in the ER Ca2+ steady state level and an increase in ER Ca2+ leakage. Our results also demonstrate that these proteins modulate SERCA-dependent ER calcium accumulation and induce apoptotic cell death.. S1T splice variants were detectable by RT-PCR at variable levels in different adult tissues, including spleen, thymus, pancreas, kidney, and liver, but not in adult and fetal skeletal muscle and heart. The relative amount of S1T, as ...

Calcium pumps transport calcium back into sarcoplasmic reticulum, ending an action potential and causing relaxation. The process of muscle contraction will continue until the action potential is terminated. Relaxation is achieved when calcium pumps have actively transported calcium back into the sarcoplasmic reticulum, reversing the changes that previously occurred in troponin. Tropomyosin is now back in its original position covering the myosin binding sites on actin, preventing crossbridges and power stroke cycling. - Stock Video Clip K005/0663

Ischemic cardiovascular disease shows trends of increasing morbidity and mortality in the United States and around the world. Current therapeutic options are limited, but the identification of key disease mechanisms and targets will inform novel therapeutic development to help decrease disease burden. One potential target is the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA), a key regulator of Ca2+ homeostasis which plays multiple roles in the cardiovascular system. SERCA catalyzes the hydrolysis of ATP and couples it to the translocation of free cytosolic Ca2+ into SR/ER stores. SERCA is redox-regulated, and is susceptible to both stimulatory and inhibitory oxidative post-translational modification. For example, oxidation of SERCA by physiological levels of nitric oxide (NO) causes reversible oxidative modification of SERCA cysteine thiols by introducing glutathione adducts. S-glutathiolation enhances SERCA Ca2+ uptake activity, which results in rapid reductions in cytoplasmic Ca2+ levels, ...

SR Ca2+ depletion, Ca2+-dependent inactivation of Ca2+ release channels, and voltage-dependent inactivation of voltage sensors are the three mechanisms that have been put forward to produce the decline of Ca2+ signals and of force, as a consequence, during continuous stimulation, whereas store-operated, voltage-gated, or excitation-coupled Ca2+ influxes, which are possibly activated during stimulation of long duration, might contribute to favor force recovery (Melzer et al., 1995; Berbey and Allard, 2009; Launikonis et al., 2010). In this study, our experimental conditions allowed us to preclude the possible involvement of sarcolemmal Ca2+ influx, and our recording conditions with a time scale of over tens of seconds did not offer the required resolution to investigate Ca2+-dependent inactivation that is known to fully develop in a few tens of milliseconds after the onset of depolarization (Schneider and Simon, 1988). These conditions allowed us to focus on SR Ca2+ depletion and ...

The secretory pathway Ca\(^{2+}\)-ATPase (SPCA) provides the Golgi apparatus with a luminal Ca\(^{2+}\) store, which is used to modulate the activity of Ca\(^{2+}\)-dependent enzymes involved in controlling the secretory pathway and post-translational modification of proteins. This Ca\(^{2+}\) store controlled by SPCA is also believed to be agonist-releasable. Regucalcin (RGN), (also known as senescence marker protein 30 (SMP30)) is believed to be a Ca\(^{2+}\)-binding protein expressed in an age-dependent manner, whereby its protein levels decrease in a number of organs as aging progresses. It has been suggested to be able to affect the activities of the sarco/endo-plasmic reticulum Ca\(^{2+}\)-ATPase (SERCA), as well as other Ca\(^{2+}\)-dependent enzymes. On the other hand, RGNs ability to bind Ca\(^{2+}\) has been argued against and this protein has been shown to modulate the activities of enzymes not involved in Ca\(^{2+}\) homeostasis, as well as have intrinsic enzymatic activity in ...

Introduction: Alzheimers disease (AD) is a neurodegenerative disorder, clinically characterized by memory dysfunction and progressive loss of cognition. No curative therapeutic or drug is available for the complete cure of this disease. The present study was aimed to evaluate the efficacy of Lactobacillus plantarum MTCC1325 in ATPases activity in the selected brain regions of rats induced with Alzheimers. Methods: For the study, 48 healthy Wistar rats were divided into four groups: group I as control group, group II as AD model (AD induced by intraperitoneal injection of D-Galactose, 120 mg/kg body weight for 6 weeks), group III as normal control rats which were orally administered only with L. plantarum MTCC1325 for 60 days, and group IV where the AD-induced rats simultaneously received oral treatment of L. plantarum MTCC1325 (10ml/kg body weight, 12×108 CFU/mL) for 60 days. The well known membrane bound transport enzymes including Na+, K+-ATPases, Ca2+-ATPases, and Mg2+-ATPases were assayed in the

These results show that vasostatin, an NH2-terminal fragment of human calreticulin, can inhibit endothelial cell proliferation in vitro, suppress neovascularization in vivo, and prevent or reduce growth of experimental tumors. Calreticulin, a ubiquitous and highly conserved protein originally identified in skeletal muscle sarcoplasmic reticulum, serves as one of the major storage depots for calcium ions within the endoplasmic reticulum and participates in calcium signaling ((34)-(36)). The NH2-domain of calreticulin, which includes aa 1-180, is the most conserved domain among the calreticulins so far cloned and has no homology to other protein sequences ((34), (35)). Although it does not bind calcium, it can bind the cytoplasmic domain of α subunits of integrins regulating cell attachment ((37)), can interact with the nuclear receptors for glucocorticoid, androgen, and retinoic acid, regulating their binding to DNA ((38)), and can, once phosphorylated, bind stem-loop structures at the 3′-end ...

Reversibly inhibits the activity of ATP2A2 in cardiac sarcoplasmic reticulum by decreasing the apparent affinity of the ATPase for Ca(2+). Modulates the contractility of the heart muscle in response to physiological stimuli via its effects on ATP2A2. Modulates calcium re-uptake during muscle relaxation and plays an important role in calcium homeostasis in the heart muscle. The degree of ATP2A2 inhibition depends on the oligomeric state of PLN. ATP2A2 inhibition is alleviated by PLN phosphorylation (By similarity).

Phospholamban Phospholamban pentamer Identifiers Symbol Phospholamban Pfam PF04272 InterPro IPR005984 SCOP 1fjk TCDB 8.A.11 OPM family 70 OPM protein 1zll

Phospholamban兔多克隆抗体(ab15000)可与小鼠, 大鼠, 兔, 仓鼠, 牛, 人, 猪, 中国仓鼠样本反应并经WB, IHC, ICC/IF实验严格验证，被7篇文献引用并得到11个独立的用户反馈。

Phospholamban兔多克隆抗体(ab85146)可与小鼠, 大鼠, 人样本反应并经WB, IHC实验严格验证。所有产品均提供质保服务，中国75%以上现货。

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