Regulation of transverse tubule ecto-ATPase activity in chicken skeletal muscle

2001 ◽  
Vol 353 (3) ◽  
pp. 521-529 ◽  
Author(s):  
Alicia MEGÍAS ◽  
M. Mar MARTÍNEZ-SENAC ◽  
Jerónimo DELGADO ◽  
Ana SABORIDO
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Cholesterol Oxidase ◽  
Cross Linking ◽  
Thermal Variation ◽  
Con A ◽  
Transverse Tubule ◽  
Membrane Components ◽  
Triton X ◽  
Chicken Skeletal Muscle

Transverse tubule (T-tubule) ecto-ATPase from chicken skeletal muscle is an integral membrane glycoprotein that seems to exist as a homodimer and exhibits unusual properties. Treatment of T-tubule membranes with concanavalin A (Con A) did not significantly affect the thermal variation of the fluorescence anisotropy of vesicles labelled with 1,6-diphenyl-1,3,5-hexatriene or trimethylammonium-1,6-diphenyl-1,3,5-hexatriene. Cross-linking of membrane components with glutaraldehyde elicited effects on ecto-ATPase activity very similar to those of Con A treatment: a severalfold increase in activity, a decrease in Triton X-100 sensitivity and a requirement to be present before ATP to exert its action. In addition, glutaraldehyde and Con A normalized the temperature dependence and the kinetic behaviour of the enzyme. Membrane-perturbing agents (detergents, alcohols and cholesterol oxidase), with the sole exception of digitonin, caused a marked decrease in ecto-ATPase activity; the prior presence of Con A prevented this inhibition, whereas when the lectin was added after the membrane perturbing agent, recovery of the activity was not always possible. The addition of nucleotides before Con A led to a suppression of ecto-ATPase stimulation; it occurred when the nucleotide was hydrolysed (ATP or UTP) and when it was not (adenosine 5′-[β,γ-imido]triphosphate) and even in the presence of 3mM Pi. A model is proposed for the complex regulatory mechanisms of chicken T-tubule ecto-ATPase that involves the occurrence of two different catalytic states in an equilibrium modulated by lectins and cross-linking agents, by the structure of the membrane and by the presence of ligands for a regulatory site.

scholarly journals Regulation of transverse tubule ecto-ATPase activity in chicken skeletal muscle

2001 ◽  
Vol 353 (3) ◽  
pp. 521 ◽  
Author(s):  
Alicia MEGÍAS ◽  
M. Mar MARTÍNEZ-SENAC ◽  
Jerónimo DELGADO ◽  
Ana SABORIDO
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Transverse Tubule ◽  
Chicken Skeletal Muscle

scholarly journals The Mg2+-ATPase of rabbit skeletal-muscle transverse tubule is a highly glycosylated multiple-subunit enzyme

1991 ◽  
Vol 278 (2) ◽  
pp. 375-380 ◽  
Author(s):  
T L Kirley
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Atp Hydrolysis ◽  
Rabbit Skeletal Muscle ◽  
Cross Linking ◽  
Low Concentrations ◽  
Sds Page ◽  
Molecular Masses ◽  
Relationship Of ◽  
Peptide Core

The Mg(2+)-ATPase present in rabbit skeletal-muscle transverse tubules is an integral membrane enzyme which has been solubilized and purified previously in this laboratory [Kirley (1988) J. Biol. Chem. 263, 12682-12689]. The present study indicates that, in addition to the approx. 100 kDa protein (distinct from the sarcoplasmic-reticulum Ca(2+)-ATPase) seen previously to co-purify with the Mg(2+)-ATPase activity, there are also proteins having molecular masses of 160, 70 and 43 kDa. The 70 and 43 kDa glycosylated proteins (50 and 31 kDa after deglycosylation) are difficult to detect by SDS/PAGE before deglycosylation, owing to the broadness of the bands. Additional purification procedures, cross-linking studies and chemical and enzymic deglycosylation studies were undertaken to determine the structure and relationship of these proteins. Both the 97 and 160 kDa proteins were demonstrated to be N-glycosylated at multiple sites, the 97 kDa protein being reduced to a peptide core of 84 kDa and the 160 kDa protein to a peptide core of 131 kDa after deglycosylation. Although the Mg(2+)-ATPase activity is resistant to a number of chemical modification reagents, cross-linking inactivates the enzyme at low concentrations. This inactivation is accompanied by cross-linking of two 97 kDa molecules to one another, suggesting that the 97 kDa protein is involved in ATP hydrolysis. The existence of several proteins along with the inhibition of ATPase activity by cross-linking is consistent with the interpretation of the susceptibility of this enzyme to inactivation by most detergents as being due to the disruption of a protein complex of associated subunits by the inactivating detergents. The 160 kDa glycoprotein can be partially resolved from the Mg(2+)-ATPase activity, and is identified by its N-terminal amino acid sequence as angiotensin-converting enzyme.

scholarly journals T-tubule membranes from chicken skeletal muscle possess an enzymic cascade for degradation of extracellular ATP

1997 ◽  
Vol 327 (3) ◽  
pp. 899-907 ◽  
Author(s):  
Jerónimo DELGADO ◽  
Gloria MORO ◽  
Ana SABORIDO ◽  
Alicia MEGÍAS
Keyword(s):  
Skeletal Muscle ◽  
Concanavalin A ◽  
Hydrolytic Activity ◽  
Extracellular Atp ◽  
Purinergic Signalling ◽  
Activity Effect ◽  
Characterization Studies ◽  
Extracellular Side ◽  
Triton X ◽  
Chicken Skeletal Muscle

The chicken T-tubule Mg2+-ATPase is an integral membrane glycoprotein that presents properties different from those of other ATPases located in skeletal muscle cells and exhibits ATP-hydrolysing activity on the extracellular side of the transverse tubule (TT) membranes. In this study we demonstrate that TT vesicles purified from chicken skeletal muscle possess ecto-ADPase and ecto-5ʹ-nucleotidase activities that, along with ecto-ATPase, are able to sequentially degrade extracellular ATP to ADP, AMP and adenosine. Characterization studies of these TT ectonucleotidases revealed remarkable differences between ecto-ATPase and ecto-ADPase activities with respect to thermal stability, temperature dependence of the hydrolytic activity, effect of ionic strength, kinetic behaviour, divalent cation preference and responses to azide, N-ethylmaleimide, NaSCN, Triton X-100 and concanavalin A. Ecto-ATPase, but not ecto-ADPase, was inhibited by a polyclonal antibody against the chicken TT ecto-ATPase. On the basis of these results we propose that ATP and ADP hydrolysis are accomplished by two distinct enzymes and therefore the TT ecto-ATPase is not an apyrase. 5ʹ-Nucleotidase activity was inhibited by adenosine 5ʹ-[α,β-methylene]diphosphate and concanavalin A, followed simple Michaelis-Menten kinetics and was released from the membranes by treatment with phosphatidylinositol-specific phospholipase C, indicating that AMP hydrolysis in T-tubules is catalysed by a typical ecto-5ʹ-nucleotidase. Results obtained from electrophoresis experiments under native conditions suggest that ecto-ATPase, ecto-ADPase and 5ʹ-nucleotidase might be associated, forming functional complexes in the T-tubule membranes. The TT ectonucleotidases constitute an enzymic cascade for the degradation of extracellular ATP that might be involved in the regulation of purinergic signalling in the muscle fibre.

Effects of diltiazem or verapamil on calcium uptake and release from chicken skeletal muscle sarcoplasmic reticulum

2005 ◽  
Vol 83 (11) ◽  
pp. 967-975 ◽  
Author(s):  
Mehrak Javadi Paydar ◽  
Abbas Pousti ◽  
Hasan Farsam ◽  
Massoud Amanlou ◽  
Shahram Ejtemaei Mehr ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Release Rate ◽  
Calcium Release ◽  
Inhibitory Effect ◽  
Channel Blockers ◽  
Uptake Inhibition ◽  
Drug Dependent ◽  
Chicken Skeletal Muscle

The purpose of this study was to determine the effects of 2 Ca2+ channel blockers, verapamil and diltiazem, on calcium loading (active Ca2+ uptake) and the following Ca2+ release induced by silver ion (Ag+) and Ca2+ from the membrane of heavy sarcoplasmic reticulum (SR) of chicken skeletal muscle. A fluorescent probe technique was employed to determine the calcium movement through the SR. Pretreatment of the medium with diltiazem and verapamil resulted in a significant decrease in the active Ca2+ uptake, with IC50 of about 290 µmol/L for verapamil and 260 µmol/L for diltiazem. Inhibition of Ca2+ uptake was not due to the development of a substantial drug-dependent leak of Ca2+ from the SR. It might, in part, have been mediated by a direct inhibitory effect of these drugs on the Ca2+ ATPase activity of the SR Ca2+ pump. We confirmed that Ca2+ channel blockers, administered after SR Ca2+ loading and before induction of Ca2+ release, caused a dose-dependent inhibition of both Ca2+- and Ag+-induced Ca2+ release rate. Moreover, if Ca2+ channel blockers were administered prior to SR Ca2+ loading, in spite of Ca2+ uptake inhibition the same reduction in Ca2+- and Ag+-induced Ca2+ release rate was seen. We showed that the inhibition of Ag+-induced Ca2+ release by L-channel blockers is more sensitive than Ca2+-induced Ca2+ release inhibition, so the IC50 for Ag+- and Ca2+-induced Ca2+ release was about 100 and 310 µmol/L for verapamil and 79 and 330 µmol/L for diltiazem, respectively. Our results support the evidence that Ca2+ channel blockers affect muscle microsome of chicken skeletal muscle by 2 independent mechanisms: first, reduction of Ca2+ uptake rate and Ca2+-ATPase activity inhibition, and second, inhibition of both Ag+- and Ca2+-induced Ca2+ release by Ca2+ release channels. These findings confirm the direct effect of Ca2+ channel blockers on calcium release channels. Our results suggest that even if the SR is incompletely preloaded with Ca2+ because of inhibition of Ca2+ uptake by verapamil and diltiazem, no impairment in Ca2+ release occurs. Key words: calcium, sarcoplasmic reticulum, diltiazem, verapamil, chicken, skeletal muscle.

scholarly journals Labelling the Ca2+-ATPase of skeletal-muscle sarcoplasmic reticulum with the cross-linker o-phthalaldehyde

1996 ◽  
Vol 317 (2) ◽  
pp. 433-437 ◽  
Author(s):  
Yamin M. KHAN ◽  
Matthew WICTOME ◽  
Malcolm EAST ◽  
Anthony G. J. LEE
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Fluorescence Emission ◽  
Molar Ratio ◽  
Cross Linking ◽  
Fluorescence Emission Spectrum ◽  
Cross Link ◽  
Subsequent Reaction ◽  
Cross Linker

The Ca2+-ATPase in the sarcoplasmic reticulum of skeletal muscle reacts with o-phthalaldehyde (OPA) to form a fluorescent isoindole product. The stoichiometry of labelling of the ATPase is 9 nmol of isoindole/mg of ATPase, corresponding to a 1:1 molar ratio of isoindole:ATPase. There is no evidence for any intermolecular cross-linking. Isoindole formation is faster in the presence of methylamine, but the stoichiometry of labelling is unchanged, whereas in the presence of 2-mercaptoethanol the level of labelling is much higher. It is concluded that OPA reacts with a single Cys residue (defining the specificity of the reaction) in a fast step, subsequent reaction with a Lys residue to form the isoindole being rate-controlling. Labelling the ATPase with OPA in the absence of methylamine leads to total loss of ATPase activity, whereas in the presence of methylamine, the decrease in ATPase activity on reaction is small. We conclude that the loss of ATPase activity probably follows from formation of the intramolecular cross-link rather than from the initial modification of the Cys residue. Reaction with OPA is not affected by the presence of ATP, ADP or Ca2+, so that the reactive Cys is not part of a ligand-binding site. The fluorescence emission spectrum of the labelled ATPase indicates a hydrophobic environment for the isoindole ring.

scholarly journals Common structural domains in the sarcoplasmic reticulum Ca-ATPase and the transverse tubule Mg-ATPase.

1987 ◽  
Vol 104 (3) ◽  
pp. 461-472 ◽  
Author(s):  
E Damiani ◽  
A Margreth ◽  
A Furlan ◽  
A S Dahms ◽  
J Arnn ◽  
...  
Keyword(s):  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Peptide Mapping ◽  
Polyclonal Antibodies ◽  
Integral Membrane Protein ◽  
Amino Acid Residues ◽  
Con A ◽  
Transverse Tubule ◽  
Immunological Relationship

Transverse tubule (TT) membranes isolated from chicken skeletal muscle possess a very active magnesium-stimulated ATPase (Mg-ATPase) activity. The Mg-ATPase has been tentatively identified as a 102-kD concanavalin A (Con A)-binding glycoprotein comprising 80% of the integral membrane protein (Okamoto, V.R., 1985, Arch. Biochem. Biophys., 237:43-54). To firmly identify the Mg-ATPase as the 102-kD TT component and to characterize the structural relationship between this protein and the closely related sarcoplasmic reticulum (SR) Ca-ATPase, polyclonal antibodies were raised against the purified SR Ca-ATPase and the TT 102-kD glycoprotein, and the immunological relationship between the two ATPases was studied by means of Western immunoblots and enzyme-linked immunosorbent assays (ELISA). Anti-chicken and anti-rabbit SR Ca-ATPase antibodies were not able to distinguish between the TT 102-kD glycoprotein and the SR Ca-ATPase. The SR Ca-ATPase and the putative 102-kD TT Mg-ATPase also possess common structural elements, as indicated by amino acid compositional and peptide mapping analyses. The two 102-kD proteins exhibit similar amino acid compositions, especially with regard to the population of charged amino acid residues. Furthermore, one-dimensional peptide maps of the two proteins, and immunoblots thereof, show striking similarities indicating that the two proteins share many common epitopes and peptide domains. Polyclonal antibodies raised against the purified TT 102-kD glycoprotein were localized by indirect immunofluorescence exclusively in the TT-rich I bands of the muscle cell. The antibodies substantially inhibit the Mg-ATPase activity of isolated TT vesicles, and Con A pretreatment could prevent antibody inhibition of TT Mg-ATPase activity. Further, the binding of antibodies to intact TT vesicles could be reduced by prior treatment with Con A. We conclude that the TT 102-kD glycoprotein is the TT Mg-ATPase and that a high degree of structural homology exists between this protein and the SR Ca-ATPase.

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