Effect of Diethyl Ether on the Adenosine Triphosphatase Activity and the Calcium Uptake of Fragmented Sarcoplasmic Reticulum of Rabbit Skeletal Muscle

Inesi, Giuseppe; Goodman, Joseph J.; Watanabe, Shizuo

doi:10.1016/s0021-9258(18)99505-0

Cited by 189 publications

(31 citation statements)

References 15 publications

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“…However, the curve bends downwards at high nucleotide concentrations. This behaviour contrasts with that of solubilized ATPase, but is in agreement with the previously demonstrated stimulatory effect of the nucleotide on ATP hydrolysis at high concentrations (Inesi et al, 1967;Yamamoto & Tonomura, 1967;Vianna, 1975). ATPase activity is lower in the deoxycholate-solubilized sample than in the vesicular preparation.…”

Section: The Estimation Of Non-protein-bound Deoxycholatesupporting

confidence: 90%

“…By contrast with the vesicular preparations, Lineweaver-Burk plots of solubilized preparations were linear over the whole range of MgATP concentrations (2-600pM), indicative of high-affinity interaction only of the solubilized protein with MgATP. The lack of the modulatory effect of MgATP at high nucleotide concentrations, characteristic of vesicular ATPase (Inesi et al, 1967;Yamamoto & Tonomura, 1967;Vianna, 1975), in part, accounts for the lower maximal extents of ATP hydrolysis by the deoxycholate-solubilized preparations, and raises the possibility that this phenomenon is mediated by ATPase-ATPase interactions in the membrane. It is notable in this connection that indirect evidence of a functional role of associated ATPase has been obtained by Yates & Duance (1976), who observed negative co-operativity in the binding of MgATP by (Ca2++Mg2+)-dependent ATPase in membranous form.…”

Section: Discussionmentioning

confidence: 99%

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The functional unit of calcium-plus-magnesium-ion-dependent adenosine triphosphatase from sarcoplasmic reticulum. The aggregational state of the deoxycholate-solubilized protein in an enzymically active form

Jørgensen

Lind

Røigaard-Petersen

et al. 1978

Biochemical Journal

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Vesicles consisting of (Ca(2+)+Mg(2+))-dependent ATPase (adenosine triphosphatase), and lipid were prepared from sarcoplasmic reticulum of rabbit skeletal muscle. As with non-ionic detergents [le Maire, Møller & Tanford (1976) Biochemistry15, 2336-2342] the (Ca(2+)+Mg(2+))-dependent ATPase after solubilization by deoxycholate showed a pronounced tendency to form oligomers in gel-chromatographic experiments, when eluted in the presence of deoxycholate and phosphatidylcholine. To evaluate the functional significance of oligomer formation the properties of enzymically active preparations of ATPase, solubilized by deoxycholate, were studied. Such preparations were obtained at a protein concentration of 2.5mg/ml in the presence of a high salt concentration (0.4m-KCl) and sucrose (0.3m) in the solubilization medium. Analytical ultracentrifugation of solubilized ATPase showed one protein boundary moving at the same rate as gel-chromatographically prepared monomeric ATPase (s(20,w)=6.0S). From simultaneous measurements of the diffusion coefficient an apparent molecular weight of 133000 was calculated, consistent with solubilization of ATPase in predominantly monomeric form. The enzymic activity of deoxycholate-solubilized ATPase when measured directly in the solubilization medium at optimal Ca(2+) and MgATP concentrations was about 35-50% of that of vesicular ATPase. The dependence of enzymic activity on MgATP concentration indicated that the solubilized ATPase retained high-affinity binding of MgATP, but the presence of high concentrations of the nucleotide did not stimulate activity further, in contrast with that of vesicular ATPase. The dependence of enzymic activity on the free Ca(2+) concentration was essentially the same for both solubilized and vesicular forms, indicating that interaction of ATPase with more than one molecule of Ca(2+) is required for enzyme activity. Solubilized enzyme at 20 degrees C was phosphorylated to about the same degree as vesicular ATPase. It is concluded that the catalytic activity of monomeric ATPase retains most of the features of vesicular ATPase and that extensive oligomer formation in gel-chromatographic experiments in the presence of deoxycholate probably reflects processes taking place during inactivation and delipidation of the protein.

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Section: The Estimation Of Non-protein-bound Deoxycholatesupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

The functional unit of calcium-plus-magnesium-ion-dependent adenosine triphosphatase from sarcoplasmic reticulum. The aggregational state of the deoxycholate-solubilized protein in an enzymically active form

Jørgensen

Lind

Røigaard-Petersen

et al. 1978

Biochemical Journal

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“…In fact, the process of active transport, as indicated by calcium-activated ATPase, is not inhibited by the ionophores. On the contrary, the burst of ATP hydrolysis is prolonged, as it occurs in experimental conditions where calcium filling of the vesicles is prevented by induction of calcium "leak" (28,33). Furthermore the continuous draining off of Ca ++ from SR vesicles induced by the ionophore prevents the inhibitory effect of accumulated Ca + + on ATPase activity (34) It can be excluded that in the experiments with X-537 A and A 23187, the induction of calcium "leak" in SR is due to gross structural effects, such as interruption of membrane continuity.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Calcium Ionophores on Fragmented Sarcoplasmic Reticulum

Scarpa

Baldassare

Inesi

1972

The Journal of General Physiology

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212

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X-537 A and A 23187, two antibiotics which form liphophilic complexes with divalent cations, function as ionophores in vesicular fragments of sarcoplasmic reticulum (SR). Addition of either ionophore to SR preloaded with calcium in the presence of adenosine triphosphate (ATP), causes rapid release of calcium. Furthermore, net calcium accumulation by SR is prevented, when the ionophores are added to the reaction mixture before ATP. On the contrary, ATP-independent calcium binding to SR is not inhibited. This effect is specific for the two antibiotics and could not be reproduced, either .by inactive derivatives, or by other known ionophores. Neither ionophore produces alterations of the electron microscopic appearance of SR membranes or inhibition of the calcium-dependent ATPase. In fact, the burst of ATP hydrolysis obtained on addition of calcium, is prolonged in the presence of the ionophores. Lanthanum inhibits ATP-independent calcium binding to SR, ATP-dependent calcium accumulation and calcium-dependent ATPase. However, addition of lanthanum to SR preloaded in the presence of ATP, does not cause calcium release. The reported experiments indicated that: (a) ATPdependent calcium accumulation by SR results in primary formation of calcium ion gradients across the membrane. (b) Most of the accumulated calcium is not available for displacement by lanthanum on the outer surface of the membrane. (c) Calcium ionophores induce rapid equilibration of the gradients, by facilitating cation diffusion across the membrane.

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“…ports have included studies of FSR during calcium uptake and following various degradative procedures (2,5,(8)(9)(10)(11)(12)(13)(14)(15) . Several questions have arisen as a result of these investigations :…”

Section: Introductionmentioning

confidence: 99%

Ultrastructure of Sarcoplasmic Reticulum Preparations

Deamer

Baskin

1969

The Journal of Cell Biology

190

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Fragmented sarcoplasmic reticulum (FSR) from rabbit muscle was examined by positive staining, negative staining, and freeze-etch electron microscopic techniques in the absence and presence of calcium transport conditions. The existence of 30–40 A particles covering the outer surface of FSR vesicles was confirmed by two different negative stains in unfixed, glutaraldehyde-fixed and osmium tetroxide-fixed material. Freeze-etch microscopy revealed a second type of particle, 80–90 A in diameter, on the fractured surfaces of FSR vesicles. Following calcium oxalate accumulation, negative and positive staining techniques provided evidence for large nodular deposits within FSR vesicles which probably correspond to calcium oxalate crystals and are responsible for increments in turbidity during calcium oxalate accumulation. The most probable configuration of FSR vesicles in solution is spherical. "Tadpole" or tubular configurations were not seen by freeze-etch microscopy, positive staining, or in prefixed negatively stained material.

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Effect of Diethyl Ether on the Adenosine Triphosphatase Activity and the Calcium Uptake of Fragmented Sarcoplasmic Reticulum of Rabbit Skeletal Muscle

Cited by 189 publications

References 15 publications

The functional unit of calcium-plus-magnesium-ion-dependent adenosine triphosphatase from sarcoplasmic reticulum. The aggregational state of the deoxycholate-solubilized protein in an enzymically active form

The functional unit of calcium-plus-magnesium-ion-dependent adenosine triphosphatase from sarcoplasmic reticulum. The aggregational state of the deoxycholate-solubilized protein in an enzymically active form

The Effect of Calcium Ionophores on Fragmented Sarcoplasmic Reticulum

Ultrastructure of Sarcoplasmic Reticulum Preparations

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