scholarly journals d-myo-inositol 1,4,5-trisphosphate phosphatase in skeletal muscle

1988 ◽  
Vol 254 (2) ◽  
pp. 525-529 ◽  
Author(s):  
D Milani ◽  
P Volpe ◽  
T Pozzan
Keyword(s):  
Skeletal Muscle ◽  
Membrane Fraction ◽  
Main Pulmonary Artery ◽  
Total Activity ◽  
Rabbit Brain ◽  
Contraction Coupling ◽  
Inositol 1,4,5 Trisphosphate ◽  
Membrane Bound ◽  
Pulmonary Artery Smooth Muscle ◽  
Fast Twitch

The presence and subcellular distribution of D-myo-inositol 1,4,5-trisphosphate phosphatase (InsP3ase) in rabbit fast-twitch skeletal muscle were investigated. A specific InsP3ase was found in both sarcotubular-membrane and soluble fractions. Membrane-bound InsP3ase accounted for 60-65% of total activity. The InsP3ase was detected both on the surface membranes and on the InsP3-sensitive intracellular Ca2+ store, i.e. the sarcoplasmic reticulum. The Km for inositol 1,4,5-trisphosphate (InsP3) ranged between 15 and 18 microM, and the highest Vmax. (19.6 nmol of InsP3 hydrolysed/min per mg of protein) was measured in a membrane fraction enriched in transverse tubules. Several known inhibitors of InsP3ase, e.g. 2,3-bisphosphoglycerate, CdCl2 and EDTA, were active on skeletal-muscle InsP3ase. Total InsP3ase activity of both rabbit and frog skeletal muscle was comparable with that of rabbit brain, liver and main pulmonary artery (smooth muscle). The present results are consistent with the hypothesis that InsP3 plays a role in excitation-contraction coupling in skeletal muscle [Volpe, Salviati, Di Virgilio & Pozzan (1985) Nature (London) 316, 347-349].

Extracellular divalent cations in excitation–contraction coupling: hypertonic solution effects

1982 ◽  
Vol 60 (4) ◽  
pp. 440-445
Author(s):  
Isao Oota ◽  
Isao Kosaka ◽  
Torao Nagai ◽  
Hideyo Yabu
Keyword(s):  
Skeletal Muscle ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Hypertonic Solution ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Skeletal Muscle Fibers ◽  
Membrane Bound

It is the purpose of this article to point out that the membrane-bound Ca plays an important role in excitation–contraction (E–C) coupling of skeletal muscle fibers and that other divalent cations are unable to substitute for this role of membrane-bound Ca.

Roles of extracellular and "trigger" calcium ions in excitation–contraction coupling in skeletal muscle

1982 ◽  
Vol 60 (4) ◽  
pp. 427-439 ◽  
Author(s):  
George B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Experimental Technique ◽  
Calcium Ions ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
New Findings ◽  
Membrane Bound ◽  
Stimulation Of

The experimental observations leading to the development of the "trigger" calcium hypothesis of excitation–contraction (E–C) coupling in skeletal muscle are discussed. Also considered in some detail are the experimental technique problems which interfere with the demonstration of this role for calcium. New findings reported are observations showing that in a zero Ca2+ solution after a delay of about 6–10 min, there is a stimulation of Ca2+ efflux. This is of sufficient size, even in very small toe muscles, to restore the twitch which previously had been reduced in size in the zero Ca2+. In studies with isolated fibre preparations it was demonstrated that depolarization contractures required extracellular Ca2+ ions for E–C coupling whereas twitches could use membrane-bound "trigger" calcium ions. Thus in zero Ca2+ the contractures were eliminated in a few seconds but twitch elimination took a few minutes. Finally, the roles in E–C coupling played by "trigger" and extracellular Ca2+ ions are summarized and discussed.

The Chemical Transmission Mechanism of Excitation-Contraction Coupling in Skeletal Muscle

Physiology ◽  
1987 ◽  
Vol 2 (5) ◽  
pp. 182-186 ◽  
Author(s):  
J Vergara ◽  
K Asotra
Keyword(s):  
Skeletal Muscle ◽  
Action Potential ◽  
Calcium Release ◽  
Transmission Mechanism ◽  
Temperature Dependent ◽  
Transverse Tubules ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Vertebrate Muscle ◽  
Inositol 1,4,5 Trisphosphate

There is a temperature-dependent lag between depolarization of transverse tubules by the action potential and onset of calcium release from the sacromplasmic reticulum that reveals the occurrence of a chemical step in excitation-contraction coupling. Recent studies suggest that in vertebrate muscle inositol 1,4,5-trisphosphate may act as a chemical link in this process.

scholarly journals Turkey erythrocytes possess a membrane-associated inositol 1,4,5-trisphosphate 3-kinase that is activated by Ca2+ in the presence of calmodulin

1987 ◽  
Vol 248 (2) ◽  
pp. 489-493 ◽  
Author(s):  
A J Morris ◽  
C P Downes ◽  
T K Harden ◽  
R H Michell
Keyword(s):  
Membrane Protein ◽  
Membrane Fraction ◽  
Inositol 1,4,5 Trisphosphate ◽  
Membrane Bound

Turkey erythrocytes contain soluble and particulate kinase activities which catalyse the ATP-dependent phosphorylation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]. The particle-bound activity accounts for approximately one-quarter of the total cellular Ins(1,4,5)P3 kinase, when assayed at a [Ca2+] of 10 nM. The particle-bound Ins(1,4,5)P3 kinase is not washed from the membrane by 0.6 M-KCl, yet may be solubilized by a variety of detergents. This suggests that it is an intrinsic membrane protein. The product of the membrane-bound Ins(1,4,5)P3 kinase is inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4], identifying the enzyme as an Ins(1,4,5)P3 3-kinase. In the presence of calmodulin, the membrane-associated Ins(1,4,5)P3 3-kinase is activated as [Ca2+] is increased over the range 0.2-1.0 microM. Under these conditions, the rates of dephosphorylation of Ins(1,3,4,5)P4 and Ins(1,4,5)P3 by phosphatases in the membrane fraction are unchanged.

Role of inositol 1,4,5-trisphosphate in excitation-contraction coupling in skeletal muscle

FEBS Letters ◽  
1986 ◽  
Vol 197 (1-2) ◽  
pp. 1-4 ◽  
Author(s):  
Pompeo Volpe ◽  
Francesco Di Virgilio ◽  
Tullio Pozzan ◽  
Giovanni Salviati
Keyword(s):  
Skeletal Muscle ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Inositol 1,4,5 Trisphosphate
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