Location of endoplasmic reticulum relative to sarcoplasmic reticulum in cultured chick myotubes

1997 ◽  
Vol 25 (1) ◽  
pp. 9S-9S
Author(s):  
IRIS D. A. van GOETHEM ◽  
JOHN CHAD ◽  
ANTHONY G. LEE ◽  
STEVEN D. JANE ◽  
J. MALCOLM EAST
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum

The Endoplasmic Reticulum-Sarcoplasmic Reticulum Connection

1993 ◽  
Vol 209 (1) ◽  
pp. 140-148 ◽  
Author(s):  
Antonello Villa ◽  
Paola Podini ◽  
Alessandra Nori ◽  
Maria Carla Panzeri ◽  
Adelina Martini ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum

cADP-ribose releases Ca2+ from cardiac sarcoplasmic reticulum independently of ryanodine receptor

1997 ◽  
Vol 273 (3) ◽  
pp. H1082-H1089 ◽  
Author(s):  
P. Lahouratate ◽  
J. Guibert ◽  
J. F. Faivre
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Sea Urchin ◽  
Calcium Release ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Consistent Effect ◽  
Cyclic Adp Ribose

Cyclic ADP-ribose (cADPR), an endogenous metabolite of beta-NAD+, activates Ca2+ release from endoplasmic reticulum in sea urchin eggs via the ryanodine receptor (RyR) pathway. A similar role has been proposed in cardiac sarcoplasmic reticulum (SR), although this remains controversial. We therefore investigated the ability of cADPR to induce Ca2+ release from canine cardiac SR microsomes using fluo 3 to monitor extravesicular Ca2+ concentration. We found that cADPR induced Ca2+ release in a concentration-dependent manner, whereas neither its precursor, NAD+, nor its metabolite, ADP-ribose, elicited a consistent effect. In addition, an additive effect on calcium release between cADPR and 9-Me-7-Br-eudistomin-D (MBED), an activator of RyR, was found as well as no cross-desensitization between cADPR and MBED. Specific blockers of the RyR did not abolish the cADPR-induced Ca2+ release. These results provide evidence for cADPR-induced Ca2+ release from dog cardiac SR via a novel mechanism which is independent of RyR activation.

scholarly journals THE SARCOPLASMIC RETICULUM IN MUSCLE CELLS OF AMBLYSTOMA LARVAE

1956 ◽  
Vol 2 (4) ◽  
pp. 163-170 ◽  
Author(s):  
Keith R. Porter
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Constant Width ◽  
Muscle Cells ◽  
Cell Types ◽  
Thin Sections ◽  
System A ◽  
Structural Relationships ◽  
Complex Membrane

Electron microscopy of thin sections of muscle fibers in myotomes of Amblystoma larvae has revealed the presence of a complex, membrane-limited system of canaliculi and vesicles which form a lace-like reticulum around and among the myofibrils. This seems to correspond to the sarcoplasmic reticulum of the earlier light microscopists and the endoplasmic reticulum of other cell types. The elements constituting the reticulum are disposed in a pattern which bears a constant relation to the bands of the adjacent myofibrils and is therefore repeated in each sarcomere. At the H band the system is transversely continuous but not so at other levels. Longitudinally continuity is interrupted at the Z bands where large vesicles belonging to adjacent sarcomere segments of the system face off on opposite sides of the band. The opposing faces of these vesicles are flat and separated by a space of more or less constant width, in which are located small, finger-shaped vesicles. In view of these and other close structural relationships with the myofibrils it seems appropriate to assign to the system a role in the conduction of the excitatory impulse.

Tunneling cell processes in myocytes of stretched mouse atria

1987 ◽  
Vol 253 (2) ◽  
pp. H432-H443
Author(s):  
E. Page ◽  
G. E. Goings ◽  
B. Power ◽  
J. Upshaw-Earley
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Ionic Composition ◽  
Interstitial Space ◽  
Cytoplasmic Matrix ◽  
Cytoplasmic Structure ◽  
Section Electron ◽  
Cell Processes ◽  
Peptide Secretion

Serial section electron micrographs of mouse atria stretched in vitro show that myocytes have cell processes which tunnel into adjacent myocytes for 8 microns or more. The tunneling cell processes (TCP) (diam 4–6.2 microns) lack myofibrils and organelles associated with atrial peptide secretion. The glycogen-rich TCP cytoplasmic matrix contains conspicuous tubules and vesicles originating from endoplasmic reticulum and resembling free sarcoplasmic reticulum (SR). TCP are surrounded by a plasmalemma derived from their myocyte of origin, the plasmalemma of the tunneled myocyte, and an intervening narrow compartment continuous with the interstitial space. Profiles having the characteristics cytoplasmic structure of TCP are also found both in the interstitial space between myocytes and near the longitudinal terminations where myocyte ends about on the interstitial space. We suggest that TCP tubules and vesicles may proliferate and/or transport in response to stretch, might be free SR, and may respond to stretch-activated changes in ionic composition or potential of the surrounding myocyte and narrow intercellular compartment.

scholarly journals Detection of the membrane-calcium distribution during mitosis in Haemanthus endosperm with chlorotetracycline.

1980 ◽  
Vol 87 (1) ◽  
pp. 23-32 ◽  
Author(s):  
S M Wolniak ◽  
P K Hepler ◽  
W T Jackson
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Membrane System ◽  
Mitotic Apparatus ◽  
Calcium Distribution ◽  
Detergent Extraction ◽  
Claw Muscle ◽  
Cellular Ca ◽  
Polar Distribution ◽  
Total Elimination

The distribution of membrane-associated calcium has been determined at various stages of mitosis in Haemanthus endosperm cells with the fluorescent chelate probe chlorotetracycline (CTC). CTC fluorescence in Haemanthus has two components: punctate, because of mitochondrial and plastid membrane-Ca++; and diffuse, primarily because of Ca++ associated with endoplasmic reticulum membranes. Punctate fluorescence assumes a polar distribution throughout mitosis. Cones of diffuse fluorescence in the chromosomse-to-pole regions of the metaphase spindle appear to coincide with the kinetochore fibers; during anaphase, the cones of fluorescence coalesce and this region of the spindle exhibits uniform diffuse fluorescence. Perturbation of the cellular Ca++ distribution by treatment with lanthanum, procaine, or EGTA results in a loss of diffuse fluorescence with no accompanying change in the intensity of punctate fluorescence. Detergent extraction of cellular membranes causes a total elimination of CTC fluorescence. CTC fluorescence of freshly teased crayfish claw muscle sarcoplasmic reticulum coincides with the A bands and is reduced by perfusion with lanthanum, procaine, and EGTA in a manner similar to that for diffuse fluorescence in the endosperm cells. These results are consistent with the hypothesis that a membrane system in the chromosome-to-pole region of the mitotic apparatus functions in the localized release of sequestered Ca++, thereby regulating the mechanochemical events of mitosis.

scholarly journals Vesicle budding from endoplasmic reticulum is involved in calsequestrin routing to sarcoplasmic reticulum of skeletal muscles

2004 ◽  
Vol 379 (2) ◽  
pp. 505-512 ◽  
Author(s):  
Alessandra NORI ◽  
Elena BORTOLOSO ◽  
Federica FRASSON ◽  
Giorgia VALLE ◽  
Pompeo VOLPE
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Golgi Complex ◽  
Skeletal Muscles ◽  
Muscle Fibres ◽  
Vesicle Budding ◽  
Er Exit Sites ◽  
Skeletal Muscle Fibres ◽  
Mutant Forms

CS (calsequestrin) is an acidic glycoprotein of the SR (sarcoplasmic reticulum) lumen and plays a crucial role in the storage of Ca2+ and in excitation–contraction coupling of skeletal muscles. CS is synthesized in the ER (endoplasmic reticulum) and is targeted to the TC (terminal cisternae) of SR via mechanisms still largely unknown, but probably involving vesicle transport through the Golgi complex. In the present study, two mutant forms of Sar1 and ARF1 (ADP-ribosylation factor 1) were used to disrupt cargo exit from ER-exit sites and intra-Golgi trafficking in skeletal-muscle fibres respectively. Co-expression of Sar1-H79G (His79→Gly) and recombinant, epitope-tagged CS, CSHA1 (where HA1 stands for nine-amino-acid epitope of the viral haemagglutinin 1), barred segregation of CSHA1 to TC. On the other hand, expression of ARF1-N126I altered the subcellular localization of GM130, a cis-medial Golgi protein in skeletal-muscle fibres and myotubes, without interfering with CSHA1 targeting to either TC or developing SR. Thus active budding from ER-exit sites appears to be involved in CS targeting and routing, but these processes are insensitive to modification of intracellular vesicle trafficking and Golgi complex disruption caused by the mutant ARF1-N126I. It also appears that CS routing from ER to SR does not involve classical secretory pathways through ER–Golgi intermediate compartments, cis-medial Golgi and trans-Golgi network.

scholarly journals Ethanol has different effects on Ca2+-transport ATPases of muscle, brain and blood platelets

1995 ◽  
Vol 312 (3) ◽  
pp. 733-737 ◽  
Author(s):  
F Mitidieri ◽  
L de Meis
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Blood Platelets ◽  
Activity Increase ◽  
Low Concentrations ◽  
Biphasic Effect ◽  
Transport Atpases

The effects of ethanol on different sarco/endoplasmic reticulum Ca(2+)-transport ATPases (SERCAs) were studied. In sarcoplasmic reticulum vesicles, ethanol concentrations varying from 5 to 20% promoted a progressive inhibition of Ca2+ uptake, enhancement of Ca2+ efflux, activation of the ATPase activity, increase of the enzyme phosphorylation by ATP and inhibition of enzyme phosphorylation by P1. The effects of ethanol on Ca2+ uptake and Ca2+ efflux were antagonized by Mg2+, P(i) and spermine. The increased efflux promoted by ethanol was antagonized by Ca2+ and thapsigargin. In brain and platelet vesicles a biphasic effect of ethanol was observed, so that activation occurred at low concentrations (5-10%) and inhibition at higher concentrations. The activation was not observed with the use of n-propanol and n-butanol. Different from the situation in sarcoplasmic reticulum, the decrease of the Ca2+ uptake in brain and platelet vesicles was associated with an inhibition of the ATPase activity. Mg2+ and P(i) antagonized the enhancement of Ca2+ efflux and the inhibition of Ca2+ uptake promoted by ethanol. However, thapsigargin and Ca2+ did not arrest the Ca2+ efflux promoted by ethanol in brain and platelet preparations. These results suggest that, in sarcoplasmic reticulum vesicles, ethanol uncouples the pump, promoting its activity as a Ca2+ channel. The SERCA isoform found in skeletal muscle has different properties from the isoforms found in brain and blood platelets.

scholarly journals Anti-apoptotic protein Bcl-2 interacts with and destabilizes the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA)

2004 ◽  
Vol 383 (2) ◽  
pp. 361-370 ◽  
Author(s):  
Elena S. DREMINA ◽  
Victor S. SHAROV ◽  
Keshava KUMAR ◽  
Asma ZAIDI ◽  
Elias K. MICHAELIS ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Conformational Transition ◽  
Direct Interaction ◽  
Molar Ratio ◽  
Endoplasmic Reticulum Calcium ◽  
Oxidative Inactivation ◽  
Complete Inactivation

The anti-apoptotic effect of Bcl-2 is well established, but the detailed mechanisms are unknown. In the present study, we show in vitro a direct interaction of Bcl-2 with the rat skeletal muscle SERCA (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase), leading to destabilization and inactivation of the protein. Recombinant human Bcl-2Δ21, a truncated form of Bcl-2 with a deletion of 21 residues at the C-terminal membrane-anchoring region, was expressed and affinity-purified as a glutathione S-transferase fusion protein. Bcl-2Δ21 co-immunoprecipitated and specifically interacted with SERCA in an in vitro-binding assay. The original level of Bcl-2 in sarcoplasmic reticulum vesicles was very low, i.e. hardly detectable by immunoblotting with specific antibodies. The addition of Bcl-2Δ21 to the sarcoplasmic reticulum resulted in the inhibition of the Ca2+-ATPase activity dependent on the Bcl-2Δ21/SERCA molar ratio and incubation time. A complete inactivation of SERCA was observed after 2.5 h of incubation at approx. 2:1 molar ratio of Bcl-2Δ21 to SERCA. In contrast, Bcl-2Δ21 did not significantly change the activity of the plasma-membrane Ca2+-ATPase. The redox state of the single Cys158 residue in Bcl-2Δ21 and the presence of GSH did not affect SERCA inhibition. The interaction of Bcl-2Δ21 with SERCA resulted in a conformational transition of SERCA, assessed through a Bcl-2-dependent increase in SERCA thiols available for the labelling with a fluorescent reagent. This partial unfolding of SERCA did not lead to a higher sensitivity of SERCA towards oxidative inactivation. Our results suggest that the direct interaction of Bcl-2 with SERCA may be involved in the regulation of apoptotic processes in vivo through modulation of cytoplasmic and/or endoplasmic reticulum calcium levels required for the execution of apoptosis.

Sign in / Sign up

Export Citation Format

Share Document