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001-es BibID:	BIBFORM049405
Első szerző:	Altafaj, Xavier
Cím:	The scorpion toxin maurocalcine; a tool to study the excitation-contraction coupling in skeletal muscle / X. Altafaj, K. Mabrouk, I. Jona, L. Csernoch, M. De Waard, M. Ronjat
Dátum:	2004
Megjegyzések:	Maurocalcine (MCa) ? isolated from the venom of the Scorpio Maurus Palmatus has been described as an extremely potent modulator of the sarcoplasmic reticulum calcium release channel (CRC/RyR). Using single channel bilayer electrophysiology and confocal laser scanning microscopy we have shown that MCa is capable of altering the open probability and the gating characteristics of CRC/RyR by inducing long lasting subconductance states (LLSS). LLSS can last for several seconds. In parallel MCa induces complex event of calcium release in line-scan images. Using mutants of MCa we have demonstrated that the surface charge and/or charge distribution is the most important single parameter of the MCa effect. Altering even a single amino acid which destroys the positively charged area overwhelmingly influences the effect of the toxin on CRC/RyR. The effectiveness of the mutants is roughly proportionally with the real distance from the critical 24 residue. Their effects on the isolated channel and on the calcium release events were between those of the wild type and the ineffective Arg24Ala mutant.
Tárgyszavak:	Természettudományok Biológiai tudományok idézhető absztrakt calcium release
Megjelenés:	Journal of Muscle Research and Cell Motility. - 26 (2004), p. 59. -
További szerzők:	Mabrouk, Kamel Jóna István (1948-) (élettanász, fizikus) Csernoch László (1961-) (élettanász) De Waard, Michel Ronjat, Michel
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001-es BibID:	BIBFORM001016
Első szerző:	Altafaj, Xavier
Cím:	Maurocalcine interacts with the cardiac ryanodine receptor without inducing channel modification / Altafaj X., France J., Almássy J., Jóna I., Rossi D., Sorrentino V., Mabrouk K., De Waard M., Ronjat M.
Dátum:	2007
Megjegyzések:	We have previously shown that MCa (maurocalcine), a toxin from the venom of the scorpion Maurus palmatus, binds to RyR1 (type 1 ryanodine receptor) and induces strong modifications of its gating behaviour. In the present study, we investigated the ability of MCa to bind to and modify the gating process of cardiac RyR2. By performing pull-down experiments we show that MCa interacts directly with RyR2with an apparent affinity of 150 nM. By expressing different domains of RyR2 in vitro, we show that MCa binds to two domains of RyR2, which are homologous with those previously identified on RyR1. The effect of MCa binding to RyR2 was then evaluated by three different approaches: (i) [H-3]ryanodine binding experiments, showing a very weak effect of MCa (up to 1 mu M), (ii) Ca2+ release measurements from cardiac sarcoplasmic reticulum vesicles, showing that MCa up to 1 mu M is unable to induce Ca2+ release, and (iii) single-channel recordings, showing that MCa has no effect on the open probability or on the RyR2 channel conductance level. Long-lasting opening events of RyR2 were observed in the presence of MCa only when the ionic current direction was opposite to the physiological direction, i.e. from the cytoplasmic face of RyR2 to its luminal face. Therefore, despite the conserved MCa binding ability of RyR1 and RyR2, functional studies show that, in contrast with what is observed with RyR1, MCa does not affect the gating properties of RyR2. These results highlight a different role of the MCa-binding domains in the gating process of RyR1 and RyR2.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Biochemical Journal 406 (2007), p. 309-315. -
További szerzők:	France, Julien Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Jóna István (1948-) (élettanász, fizikus) Rossi, Daniela Sorrentino, Vincenzo Mabrouk, Kamel De Waard, Michel Ronjat, Michel
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001-es BibID:	BIBFORM004115
Első szerző:	Lukács Balázs (élettanász)
Cím:	Charged surface area of maurocalcine determines its interaction with the skeletal ryanodine receptor / Balazs Lukacs, Monika Sztretye, Janos Almassy, Sandor Sarkozi, Beatrix Dienes, Kamel Mabrouk, Cecilia Simut, Laszlo Szabo, Peter Szentesi, Michel De Waard, Michel Ronjat, Istvan Jona, Laszlo Csernoch
Dátum:	2008
Megjegyzések:	The 33 amino acid scorpion toxin maurocalcine (MCa) has been shown to modify the gating of the skeletal-type ryanodine receptor (RyR1). Here we explored the effects of MCa and its mutants ([Ala(8)]MCa, [Ala(19)]MCa, [Ala(20)]MCa, [Ala(22)]MCa, [Ala(23)]MCa, and [Ala(24)]MCa) on RyR1 incorporated into artificial lipid bilayers and on elementary calcium release events (ECRE) in rat and frog skeletal muscle fibers. The peptides induced long-lasting subconductance states (LLSS) on RyR1 that lasted for several seconds. However, their average length and frequency were decreased if the mutation was placed farther away in the 3D structure from the critical (24)Arg residue. The effect was strongly dependent on the direction of the current through the channel. If the direction was similar to that followed by calcium during release, the peptides were 8- to 10-fold less effective. In fibers long-lasting calcium release events were observed after the addition of the peptides. The average length of these events correlated well with the duration of LLSS. These data suggest that the effect of the peptide is governed by the large charged surface formed by residues Lys(20), Lys(22), Arg(23), Arg(24), and Lys(8). Our observations also indicate that the results from bilayer experiments mimic the in situ effects of MCa on RyR1.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Biophysical Journal. - 95 : 7 (2008), p. 3497-3509. -
További szerzők:	Sztretye Mónika (1981-) (élettanász, elektrofiziológus) Almássy János (1981-) (élettanász, biológus, angol-magyar szakfordító) Sárközi Sándor (1966-) (élettanász) Dienes Beatrix (1972-) (élettanász, molekuláris biológus) Mabrouk, Kamel Simut, Cecilia Szabó László (Románia) Szentesi Péter (1967-) (élettanász) De Waard, Michel Ronjat, Michel Jóna István (1948-) (élettanász, fizikus) Csernoch László (1961-) (élettanász)
Internet cím:	elektronikus változat elektronikus változat DOI
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