Effects of perchlorate on depolarization-induced conformational changes in the junctional foot protein and Ca2+ release from sarcoplasmic reticulum
| Autor: | Masafumi Yano, Roque El-Hayek, Noriaki Ikemoto |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Conformational change
Protein Conformation Muscle Proteins Biochemistry Ryanodine receptor 2 Membrane Potentials Perchlorate chemistry.chemical_compound Protein structure medicine Animals Muscle Skeletal Membrane potential Perchlorates Ryanodine Chemistry Ryanodine receptor Osmolar Concentration Ryanodine Receptor Calcium Release Channel Depolarization Triad (anatomy) Calcium Channel Blockers Sodium Compounds Sarcoplasmic Reticulum Spectrometry Fluorescence medicine.anatomical_structure Biophysics Calcium Calmodulin-Binding Proteins Nimodipine Calcium Channels Rabbits Protein Binding |
| Zdroj: | Biochemistry. 34:12584-12589 |
| ISSN: | 1520-4995 0006-2960 |
| DOI: | 10.1021/bi00039a013 |
| Popis: | Perchlorate is one of the most potent activators of skeletal muscle excitation-contraction (E-C) coupling reported in the literature, but the detailed mechanism of its action remains to be elucidated. In an attempt to further resolve the mode of perchlorate action, the effects of increasing concentrations of perchlorate on the voltage-dependent (T-tubule-mediated) and voltage-independent portions of Ca2+ release were investigated using the isolated triad model. Low concentrations of perchlorate (< or = 10 mM) activated SR Ca2+ release only when the T-tubule moiety was chemically depolarized. Higher concentrations of perchlorate (30-100 mM), on the other hand, produced significant activation of SR Ca2+ release, regardless of whether or not the T-tubule was depolarized. In order to gain further insights, we monitored the conformational change in the junctional foot protein (JFP), which presumably is an important intermediate step in E-C coupling [Yano, M., El-Hayek, R., & Ikemoto, N. (1995) J. Biol. Chem. 270, 3017-3021], using the fluorescently labeled triad preparation. Again, low concentrations of perchlorate (< or = 10 mM) produced a preferential activation of voltage-dependent protein conformational change, while higher concentrations of perchlorate produced significant activation of voltage-independent protein conformational change. An increase in the ryanodine binding by perchlorate occurred only in the higher concentration range where the voltage-independent protein conformational change was activated. These results suggest that perchlorate activates E-C coupling by acting on at least two different steps: at lower concentrations, on the T-tubule-to-JFP signal transmission step; at higher concentrations, on the JFP directly. |
| Databáze: | OpenAIRE |
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