Movement of Ca(2+)-ATPase molecules within the sarcoplasmic/endoplasmic reticulum in skeletal muscle

1996 ◽  
Vol 109 (10) ◽  
pp. 2529-2537
Author(s):  
Z. Kaprielian ◽  
S.W. Robinson ◽  
D.M. Fambrough ◽  
P.D. Kessler

The endoplasmic reticulum undergoes rapid, microscopic changes in its structure, including extension and anastomosis of tubular elements. Such dynamism is expected to manifest itself also as rapid intermixing of membrane components, at least within subdomains of the endoplasmic reticulum. Here we present evidence of a similar dynamism in the sarcoplasmic reticulum of developing skeletal muscle. The sarcoplasmic reticulum is sometimes considered a specialized type of endoplasmic reticulum, but it appears to be a rather static set of membrane-bound elements, repetitively arranged to enwrap each sarcomere of each myofibril. Both endoplasmic reticulum and sarcoplasmic reticulum contain P-type Ca(2+)-ATPases that transport calcium from the cytosol into their lumen. In the experiments reported here, chicken and mouse cells were fused by polyethylene glycol, natural myogenic cell fusion, or Sendai virus. The redistribution of Ca(2+)-ATPase molecules between chick and mouse endoplasmic reticulum/sarcoplasmic reticulum was followed by immunofluorescence microscopy in which species-specific monoclonal antibodies to chick and mouse Ca(2+)-ATPases were used. Redistribution was time- and temperature-dependent but independent of protein synthesis as well as the method of cell fusion. Intermixing occurred on a time scale of tens of minutes at 37 degrees C. These results verify the dynamic nature of the sarcoplasmic reticulum and illustrate an aspect of the special relationship between endoplasmic reticulum and sarcoplasmic reticulum.

1977 ◽  
Vol 55 (6) ◽  
pp. 587-596 ◽  
Author(s):  
Barbara A. Manuck ◽  
Brian D. Sykes

1H nuclear magnetic resonance techniques were used to study the binding of uridine 5′-triphosphate to the Ca2+-transport ATPase (EC 3.6.1.3) of sarcoplasmic reticulum vesicles from rabbit skeletal muscle. The nuclear spin relaxation times determined for the bound nucleotide are used to characterize the rotational motion of the ATPase to which the nucleotide is bound. The results, assuming an anisotropic model for the motion of the ATPase in the membrane, place a low upper limit on the rotational correlation time of the ATPase. This indicates that the motion of the ATPase in the membrane is quite rapid when compared, for example, with the motion found for other membrane-bound proteins such as rhodopsin.


2004 ◽  
Vol 379 (2) ◽  
pp. 505-512 ◽  
Author(s):  
Alessandra NORI ◽  
Elena BORTOLOSO ◽  
Federica FRASSON ◽  
Giorgia VALLE ◽  
Pompeo VOLPE

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.


1995 ◽  
Vol 312 (3) ◽  
pp. 733-737 ◽  
Author(s):  
F Mitidieri ◽  
L de Meis

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.


1981 ◽  
Vol 197 (1) ◽  
pp. 245-248 ◽  
Author(s):  
E Damiani ◽  
R Betto ◽  
S Salvatori ◽  
P Volpe ◽  
G Salviati ◽  
...  

Antibody was raised in chickens against purified sarcoplasmic-reticulum Ca2+-activated ATPase (Ca2+-ATPase). The immunological relationship between the Ca2+-ATPase of fast-muscle and slow-muscle sarcoplasmic reticulum was investigated by a one-step and a two-step competitive enzyme-linked immunosorbent assay (ELISA). The results show marked antigenic differences between the membrane-bound Ca2+-ATPase of the sarcoplasmic-reticulum vesicles from fast muscle and slow muscle, beside differences in the membrane content of ATPase protein.


1978 ◽  
Vol 56 (6) ◽  
pp. 452-456 ◽  
Author(s):  
Donald C. Greenway ◽  
David H. MacLennan

Membrane-bound and free polyribosomes were isolated from skeletal muscle of neonatal rats and messages were translated in a rabbit reticulocyte lysate treated with a Ca2+-dependent nuclease to reduce endogenous messenger translation. Newly synthesized calsequestrin and adenosine triphosphatase (ATPase) were isolated by antibody precipitation, followed by separation of the precipitates in SDS-polyacrylamide gels. Radioactivity in calsequestrin and the ATPase were counted in gel slices. Calsequestrin and the ATPase were both found to be synthesized on membrane-bound polyribosomes. Since calsequestrin is a glycoprotein, localized in Golgi regions in early stages of muscle cell differentiation, it is probable that its synthesis follows the pathway for synthesis of secreted proteins except that its destination is the luminal space of a cellular organelle. The disposition of the ATPase during synthesis is, as yet, unknown.


1989 ◽  
Vol 257 (1) ◽  
pp. 117-123 ◽  
Author(s):  
F Wuytack ◽  
Y Kanmura ◽  
J A Eggermont ◽  
L Raeymaekers ◽  
J Verbist ◽  
...  

Smooth muscle expresses in its endoplasmic reticulum an isoform of the Ca2+-transport ATPase that is very similar to or identical with that of the cardiac-muscle/slow-twitch skeletal-muscle form. However, this enzyme differs from that found in fast-twitch skeletal muscle. This conclusion is based on two independent sets of observations, namely immunological observations and phosphorylation experiments. Immunoblot experiments show that two different antibody preparations against the Ca2+-transport ATPase of cardiac-muscle sarcoplasmic reticulum also recognize the endoplasmic-reticulum/sarcoplasmic-reticulum enzyme of the smooth muscle and the slow-twitch skeletal muscle whereas they bind very weakly or not at all to the sarcoplasmic-reticulum Ca2+-transport ATPase of the fast-twitch skeletal muscle. Conversely antibodies directed against the fast-twitch skeletal-muscle isoform of the sarcoplasmic-reticulum Ca2+-transport ATPase do not bind to the cardiac-muscle, smooth-muscle or slow-twitch skeletal-muscle enzymes. The phosphorylated tryptic fragments A and A1 of the sarcoplasmic-reticulum Ca2+-transport ATPases have the same apparent Mr values in cardiac muscle, slow-twitch skeletal muscle and smooth muscle, whereas the corresponding fragments in fast-twitch skeletal muscle have lower apparent Mr values. This analytical procedure is a new and easy technique for discrimination between the isoforms of endoplasmic-reticulum/sarcoplasmic-reticulum Ca2+-transport ATPases.


1984 ◽  
Vol 224 (2) ◽  
pp. 445-451 ◽  
Author(s):  
F Wuytack ◽  
L Raeymaekers ◽  
J Verbist ◽  
H De Smedt ◽  
R Casteels

Membrane fractions prepared from smooth muscle of the pig stomach (antral part) contain two Ca2+-dependent phosphoprotein intermediates belonging to different Ca2+-transport ATPases. These alkali-labile phosphoproteins can be separated by electrophoresis in acid medium. The 130 kDa phosphoprotein resembles a corresponding protein in the erythrocyte membrane, whereas the 100 kDa protein resembles that of the Ca2+-transport ATPase in sarcoplasmic reticulum from skeletal muscle. These resemblances are expressed in terms of Mr, reaction to La3+ and in a similar proteolytic degradation pattern. The presence of the calmodulin-stimulated ATPase in mixed membranes from smooth muscle is confirmed by its binding of calmodulin and antibodies against erythrocyte Ca2+-transport ATPase, whereas such binding does not occur with proteins present in the presumed endoplasmic reticulum from smooth muscle.


1995 ◽  
Vol 306 (1) ◽  
pp. 35-38 ◽  
Author(s):  
J C Benech ◽  
H Wolosker ◽  
L de Meis

In this study, the endoplasmic Ca2+ transport ATPase of blood platelets was compared with the Ca2+ ATPase of sarcoplasmic reticulum skeletal muscle. Similar to the muscle enzyme, the Ca2+ ATPase from platelets was found to catalyse an ATP<-->P(i) exchange both in the presence and in the absence of a transmembrane Ca2+ gradient. When platelet vesicles are loaded with Ca2+ and diluted in medium containing ADP, P(i) and EGTA, the ATPase catalyses Ca2+ efflux coupled to synthesis of ATP. The stoichiometry between Ca2+ ion released and ATP synthesized by platelet Ca2+ ATPase is 1, while that of skeletal muscle is 2. Thapsigargin, a specific inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPases, inhibited both the Ca(2+)-dependent ATPase activity and the reversal of the platelet Ca2+ pump. The possibility is discussed that the differences observed between the two transport systems is related to the distinct amino acid sequences of the enzymes.


2007 ◽  
Vol 213 (2) ◽  
pp. 464-474 ◽  
Author(s):  
Alexandra Divet ◽  
Silvia Paesante ◽  
Cristiano Grasso ◽  
Dario Cavagna ◽  
Cecilia Tiveron ◽  
...  

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