scholarly journals Fatty acyl-CoA–acyl-CoA-binding protein complexes activate the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum

1997 ◽  
Vol 325 (2) ◽  
pp. 423-428 ◽  
Author(s):  
Rosella FULCERI ◽  
Jens KNUDSEN ◽  
Roberta GIUNTI ◽  
Pompeo VOLPE ◽  
Alessandra NORI ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Binding Sites ◽  
Protein Complexes ◽  
Binding Protein ◽  
Fatty Acyl ◽  
Channel Activity ◽  
Experimental Conditions ◽  
Release Channel ◽  
High Affinity ◽  
Terminal Cisternae

We previously reported that fatty acyl-CoA esters activate ryanodine receptor/Ca2+ release channels in a terminal cisternae fraction from rabbit skeletal muscle [Fulceri, Nori, Gamberucci, Volpe, Giunti and Benedetti (1994) Cell Calcium 15, 109–116]. Skeletal muscle cytosol contains a high-affinity fatty acyl-CoA-binding protein (ACBP) [Knudsen, Hojrup, Hansen, H. O., Hansen, H. F. and Roepstorff (1989) Biochem. J. 262, 513–519]. We show here that palmitoyl-CoA (PCoA) in a complex with a molar excess of bovine ACBP causes a discrete Ca2+ efflux or allows Ca2+ release from the Ca2+-preloaded terminal cisternae fraction by sub-optimal caffeine concentrations. Both effects were abolished by elevating the free [Mg2+] in the system, which inhibits the Ca2+ release channel activity. Sensitization towards caffeine was a function of both the concentration of the complex and the [PCoA]-to-[ACBP] ratio. In all experimental conditions the calculated free [PCoA] was no more than 50 nM, and such concentrations by themselves were inactive on Ca2+ release channels. The KD for PCoA binding was approx. 2 nM for bovine and yeast ACBP, and slightly higher (8 nM) for rat ACBP. The PCoA–rat ACBP complex behaved in the same manner as the PCoA–bovine ACBP complex, whereas the ester complexed with yeast ACBP was more active in activating/sensitizing Ca2+ efflux. A non-hydrolysable analogue of PCoA bound to (bovine) ACBP also sensitized the Ca2+ release channel towards caffeine. These findings indicate that fatty acyl-CoA–ACBP complexes either interact directly with one or more components in the terminal cisternae membranes or, through interaction with the component(s), donate the fatty acyl-CoA esters to high-affinity binding sites of the membrane, thus affecting (and possibly regulating) Ca2+ release channel activity.

Modulation of skeletal muscle Ca2(+)-release channel activity by sphingosine

1997 ◽  
Vol 272 (5) ◽  
pp. C1465-C1474 ◽  
Author(s):  
D. H. Needleman ◽  
B. Aghdasi ◽  
A. B. Seryshev ◽  
G. J. Schroepfer ◽  
S. L. Hamilton
Keyword(s):  
Skeletal Muscle ◽  
Lipid Bilayers ◽  
Binding Protein ◽  
Planar Lipid Bilayers ◽  
Dependent Manner ◽  
Carboxy Terminus ◽  
Release Channel ◽  
Proteolytic Fragment ◽  
High Affinity ◽  
High Affinity Site

The effect of D-erythro-C18-sphingosine (sphingosine) and related compounds on the Ca(2+)-release channel (ryanodine binding protein) was examined on rabbit skeletal muscle membranes, on the purified ryanodine binding protein, and on the channel reconstituted into planar lipid bilayers. Sphingosine inhibited [3H]ryanodine binding to sarcoplasmic reticulum (SR) membranes in a dose-dependent manner similar to published results (R. A. Sabbadini, R. Betto, A. Teresi, G. Fachechi-Cassano, and G. Salviati. J. Biol. Chem. 267: 15475-15484, 1992). The sphingolipid also inhibited [3H]ryanodine binding to the purified ryanodine binding protein. Our results demonstrate that the inhibition of [3H]ryanodine binding by sphingosine is due to an increased rate of dissociation of bound [3H]ryanodine from SR membranes and a decreased rate of association of [3H]ryanodine to the high-affinity site. Unlike other modulators of the Ca(2+)-release channel, sphingosine can remove bound [3H]ryanodine from the high-affinity site within minutes. Sphingosine increased the rate of dissociation of [3H]ryanodine bound to a solubilized proteolytic fragment derived from the carboxy terminus of the ryanodine binding protein (cleavage at Arg4475). Sphingosine also inhibited the activity of the Ca(2+)-release channel incorporated into planar lipid bilayers. Taken together, the data provide evidence for a direct effect of sphingosine on the Ca(2+)-release channel. Sphingosine is a noncompetitive inhibitor at the high-affinity ryanodine binding site, and it interacts with a site between Arg4475 and the carboxy terminus of the Ca(2+)-release channel.

scholarly journals Effects of local anesthetics on single channel behavior of skeletal muscle calcium release channel.

1993 ◽  
Vol 101 (2) ◽  
pp. 207-233 ◽  
Author(s):  
L Xu ◽  
R Jones ◽  
G Meissner
Keyword(s):  
Skeletal Muscle ◽  
Local Anesthetics ◽  
Single Channels ◽  
Channel Activity ◽  
Quaternary Amine ◽  
Open Probability ◽  
Release Channel ◽  
High Affinity ◽  
Voltage Dependent ◽  
Regulatory Sites

The effects of the two local anesthetics tetracaine and procaine and a quaternary amine derivative of lidocaine, QX314, on sarcoplasmic reticulum (SR) Ca2+ release have been examined by incorporating the purified rabbit skeletal muscle Ca2+ release channel complex into planar lipid bilayers. Recordings of potassium ion currents through single channels showed that Ca(2+)- and ATP-gated channel activity was reduced by the addition of the tertiary amines tetracaine and procaine to the cis (cytoplasmic side of SR membrane) or trans (SR lumenal) side of the bilayer. Channel open probability was lowered twofold at tetracaine and procaine concentrations of approximately 150 microM and 4 mM, respectively. Hill coefficients of 2.0 and greater indicated that the two drugs inhibited channel activity by binding to two or more cooperatively interacting sites. Unitary conductance of the K(+)-conducting channel was not changed by 1 mM tetracaine in the cis and trans chambers. In contrast, cis millimolar concentrations of the quaternary amine QX314 induced a fast blocking effect at positive holding potentials without an apparent change in channel open probability. A voltage-dependent block was observed at high concentrations (millimolar) of tetracaine, procaine, and QX314 in the presence of 2 microM ryanodine which induced the formation of a long open subconductance. Vesicle-45Ca2+ ion flux measurements also indicated an inhibition of the SR Ca2+ release channel by tetracaine and procaine. These results indicate that local anesthetics bind to two or more cooperatively interacting high-affinity regulatory sites of the Ca2+ release channel in or close to the SR membrane. Voltage-dependent blockade of the channel by QX314 in the absence of ryanodine, and by QX314, procaine and tetracaine in the presence of ryanodine, indicated one low-affinity site within the conduction pathway of the channel. Our results further suggest that tetracaine and procaine may primarily inhibit excitation-contraction coupling in skeletal muscle by binding to the high-affinity, regulatory sites of the SR Ca2+ release channel.

Lactate inhibits Ca2+-activated Ca2+-channel activity from skeletal muscle sarcoplasmic reticulum

1997 ◽  
Vol 82 (2) ◽  
pp. 447-452 ◽  
Author(s):  
Terence G. Favero ◽  
, Anthony C. Zable ◽  
, David Colter ◽  
Jonathan J. Abramson
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Single Channel ◽  
Channel Activity ◽  
Release Channel ◽  
Muscle Lactate ◽  
Tension Development ◽  
Contraction Coupling ◽  
Single Channel Activity ◽  
High Concentrations

Favero, Terence G., Anthony C. Zable, David Colter, and Jonathan J. Abramson. Lactate inhibits Ca2+-activated Ca2+-channel activity from skeletal muscle sarcoplasmic reticulum. J. Appl. Physiol. 82(2): 447–452, 1997.—Sarcoplasmic reticulum (SR) Ca2+-release channel function is modified by ligands that are generated during about of exercise. We have examined the effects of lactate on Ca2+- and caffeine-stimulated Ca2+ release, [3H]ryanodine binding, and single Ca2+-release channel activity of SR isolated from rabbit white skeletal muscle. Lactate, at concentrations from 10 to 30 mM, inhibited Ca2+- and caffeine-stimulated [3H]ryanodine binding to and inhibited Ca2+- and caffeine-stimulated Ca2+ release from SR vesicles. Lactate also inhibited caffeine activation of single-channel activity in bilayer reconstitution experiments. These findings suggest that intense muscle activity, which generates high concentrations of lactate, will disrupt excitation-contraction coupling. This may lead to decreases in Ca2+ transients promoting a decline in tension development and contribute to muscle fatigue.

Compensatory downregulation of myocardial Ca channel in SR from dogs with heart failure

1993 ◽  
Vol 264 (3) ◽  
pp. H926-H937 ◽  
Author(s):  
C. R. Cory ◽  
L. J. McCutcheon ◽  
M. O'Grady ◽  
A. W. Pang ◽  
J. D. Geiger ◽  
...  
Keyword(s):  
Heart Failure ◽  
Ca Channel ◽  
Channel Activity ◽  
Binding Studies ◽  
Release Channel ◽  
Partial Restoration ◽  
Doberman Pinschers ◽  
Rapid Ventricular Pacing ◽  
45Ca Release ◽  
Terminal Cisternae

In this study we tested the hypothesis that the ryanodine-binding Ca-release channel activity and density of the sarcoplasmic reticulum (SR) terminal cisternae were decreased in congestive heart failure (CHF) that occurs spontaneously in doberman pinschers or experimentally with rapid ventricular pacing of mongrels. We used a novel, sensitive, and easy-to-perform microassay and demonstrated a 50% decrease in activity of the myocardial SR Ca pump and a 75% reduction in SR Ca-release channel activity in CHF. Decreases in Ca channel content were associated with increases in net Ca sequestration. 45Ca-release experiments from passively loaded SR terminal cisternae and ryanodine-binding studies confirmed a 53–68% downregulation of the Ca-release channel activity. As a consequence of release channel downregulation, there was partial restoration of net Ca sequestration activity in dogs with CHF and complete compensation in dogs with mild cardiac dysfunction. Deterioration of Ca cycling correlated with deterioration of myocardial performance, apparently due to decreased Ca-adenosinetriphosphatase (ATPase) pump and not Ca channel content. One-half the reduction in Ca-release activity could be attributed to decreased Ca sequestration and one-half to decreased Ca channel density. Downregulation of Ca channel content decreases the amplitude of the Ca cycle and maximizes the downregulation of Ca pumps that may occur. Although these adaptations may reduce cellular energy expenditure, they are likely to render the myocardium more susceptible to fatigue and failure.

scholarly journals Anti-diabetic drug binding site in a mammalian KATP channel revealed by Cryo-EM

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Gregory M Martin ◽  
Balamurugan Kandasamy ◽  
Frank DiMaio ◽  
Craig Yoshioka ◽  
Show-Ling Shyng
Keyword(s):  
Binding Sites ◽  
Katp Channel ◽  
Katp Channels ◽  
Binding Pocket ◽  
Drug Binding ◽  
Channel Activity ◽  
Nucleotide Binding Domain ◽  
High Affinity ◽  
Drug Binding Site ◽  
First Time

Sulfonylureas are anti-diabetic medications that act by inhibiting pancreatic KATP channels composed of SUR1 and Kir6.2. The mechanism by which these drugs interact with and inhibit the channel has been extensively investigated, yet it remains unclear where the drug binding pocket resides. Here, we present a cryo-EM structure of a hamster SUR1/rat Kir6.2 channel bound to a high-affinity sulfonylurea drug glibenclamide and ATP at 3.63 Å resolution, which reveals unprecedented details of the ATP and glibenclamide binding sites. Importantly, the structure shows for the first time that glibenclamide is lodged in the transmembrane bundle of the SUR1-ABC core connected to the first nucleotide binding domain near the inner leaflet of the lipid bilayer. Mutation of residues predicted to interact with glibenclamide in our model led to reduced sensitivity to glibenclamide. Our structure provides novel mechanistic insights of how sulfonylureas and ATP interact with the KATP channel complex to inhibit channel activity.

scholarly journals Anti-diabetic drug binding site in KATP channels revealed by Cryo-EM

2017 ◽  
Author(s):  
Gregory M. Martin ◽  
Balamurugan Kandasamy ◽  
Frank DiMaio ◽  
Craig Yoshioka ◽  
Show-Ling Shyng
Keyword(s):  
Binding Site ◽  
Binding Sites ◽  
Katp Channels ◽  
Binding Pocket ◽  
Drug Binding ◽  
Channel Activity ◽  
Nucleotide Binding Domain ◽  
High Affinity ◽  
Drug Binding Site ◽  
First Time

AbstractSulfonylureas are anti-diabetic medications that act by inhibiting pancreatic KATP channels composed of SUR1 and Kir6.2. The mechanism by which these drugs interact with and inhibit the channel has been extensively investigated, yet it remains unclear where the drug binding pocket resides. Here, we present a cryo-EM structure of the channel bound to a high-affinity sulfonylurea drug glibenclamide and ATP at 3.8Å resolution, which reveals in unprecedented details of the ATP and glibenclamide binding sites. Importantly, the structure shows for the first time that glibenclamide is lodged in the transmembrane bundle of the SUR1-ABC core connected to the first nucleotide binding domain near the inner leaflet of the lipid bilayer. Mutation of residues predicted to interact with glibenclamide in our model led to reduced sensitivity to glibenclamide. Our structure provides novel mechanistic insights of how sulfonylureas and ATP interact with the KATP channel complex to inhibit channel activity.

High-affinity [3H]PN200-110 and [3H]ryanodine binding to rabbit and frog skeletal muscle

1994 ◽  
Vol 266 (2) ◽  
pp. C462-C466 ◽  
Author(s):  
K. Anderson ◽  
A. H. Cohn ◽  
G. Meissner
Keyword(s):  
Skeletal Muscle ◽  
Rabbit Skeletal Muscle ◽  
Muscle Membrane ◽  
Scatchard Analysis ◽  
Physical Interaction ◽  
Frog Skeletal Muscle ◽  
Release Channel ◽  
High Affinity ◽  
Voltage Dependent ◽  
Student’S T

In vertebrate skeletal muscle, the voltage-dependent mechanism of sarcoplasmic reticulum (SR) Ca2+ release, commonly referred to as excitation-contraction (E-C) coupling, is mediated by the voltage-sensing dihydropyridine receptor (DHPR), which is believed to affect SR Ca2+ release through a physical interaction with the SR ryanodine receptor (RYR)/Ca2+ release channel. Scatchard analysis of ligand binding of [3H]PN200-110 to the DHPR and [3H]ryanodine to the RYR indicated the presence of high-affinity sites in muscle homogenates, with maximum binding (Bmax) values of 72 +/- 26 and 76 +/- 30 pmol/g wet wt for rabbit skeletal muscle, and 27 +/- 14 and 44 +/- 13 pmol/g wet wt for frog skeletal muscle, respectively. The Bmax values corresponded to a PN200-110-to-ryanodine binding ratio of 0.98 +/- 0.26 and 0.61 +/- 0.24 for rabbit and frog skeletal muscle, respectively, and were found by Student's t test to be significantly different (P < 0.02, n = 7). These results are compared with measurements with isolated rabbit skeletal muscle membrane fractions and discussed in relation to our current understanding of the mechanism of E-C coupling in skeletal muscle.

Expression and binding activity of the glucocorticoid receptor are upregulated in septic muscle

2002 ◽  
Vol 282 (2) ◽  
pp. R509-R518 ◽  
Author(s):  
Xiaoyan Sun ◽  
David R. Fischer ◽  
Timothy A. Pritts ◽  
Curtis J. Wray ◽  
Per-Olof Hasselgren
Keyword(s):  
Skeletal Muscle ◽  
Glucocorticoid Receptor ◽  
Binding Sites ◽  
Cecal Ligation ◽  
Binding Activity ◽  
Scatchard Analysis ◽  
Regulatory Effect ◽  
Hormone Binding ◽  
Experimental Conditions ◽  
Protein Levels

We examined the influence of sepsis, induced by cecal ligation and puncture in rats, on the protein and gene expression and hormone binding activity of the glucocorticoid receptor (GR) in skeletal muscle. Sepsis resulted in increased GR mRNA and protein levels and upregulated hormone binding activity in extensor digitorum longus and soleus muscles. Scatchard analysis suggested that the increased GR hormone binding activity reflected an increased number of hormone binding sites, whereas receptor affinity for glucocorticoids was unchanged. The GR antagonist RU-38486 blocked the sepsis-induced increase in GR expression and hormone binding activity, implicating a positive regulatory effect of glucocorticoids on GR expression and binding activity under the present experimental conditions. The results suggest that glucocorticoid-dependent metabolic changes in skeletal muscle during sepsis may reflect not only high circulating glucocorticoid levels but increased amounts and hormone binding activity of the GR as well.

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