Functional Characterization of the Recombinant Type 3 Ca2+Release Channel (Ryanodine Receptor) Expressed in HEK293 Cells

Electron-microscopic analysis was used to show that invertebrate muscle has feetlike structures on the sarcoplasmic reticulum (SR) displaying the typical four-subunit appearance of the calcium (Ca2+) release channel/ryanodine receptor (RyR) observed in vertebrate skeletal muscle (K. E. Loesser, L. Castellani, and C. Franzini-Armstrong. J. Muscle Res. Cell Motil. 13: 161–173, 1992). SR vesicles from invertebrate muscle exhibited specific ryanodine binding and single channel currents that were activated by Ca2+, caffeine, and ATP and inhibited by ruthenium red. The single channel conductance of this invertebrate RyR was lower than that of the vertebrate RyR (49 and 102 pS, respectively). Activation of lobster and scallop SR Ca2+ release channel, in response to cytoplasmic Ca2+ (1 nM–10 mM), reflected a bell-shaped curve, as is found with the mammalian RyR. In contrast to a previous report (J.-H. Seok, L. Xu, N. R. Kramarcy, R. Sealock, and G. Meissner. J. Biol. Chem. 267: 15893–15901, 1992), our results show that regulation of the invertebrate and vertebrate RyRs is quite similar and suggest remarkably similar paths in these diverse organisms.

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Functional properties of the native type 3 ryanodine receptor Ca2+-release channel from canine diaphragm

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-79-4-310 ◽

2001 ◽

Vol 79 (4) ◽

pp. 310-319 ◽

Cited By ~ 1

Author(s):

Eric Rousseau ◽

Sonia Proteau

Keyword(s):

Ryanodine Receptor ◽

Functional Properties ◽

Release Channel ◽

Type 3

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Characterization of an N-terminal Nav1.5 channel variant – a potential risk factor for arrhythmias and sudden death?

BMC Medical Genetics ◽

10.1186/s12881-020-01170-3 ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Stefanie Scheiper-Welling ◽

Paolo Zuccolini ◽

Oliver Rauh ◽

Britt-Maria Beckmann ◽

Christof Geisen ◽

...

Keyword(s):

Sudden Death ◽

Functional Characterization ◽

Missense Variant ◽

Hek293 Cells ◽

Patch Clamp Technique ◽

Gene Encoding ◽

Heterozygous Variant ◽

Cardiac Sodium Channel ◽

Electrophysiological Measurements

Abstract Background Alterations in the SCN5A gene encoding the cardiac sodium channel Nav1.5 have been linked to a number of arrhythmia syndromes and diseases including long-QT syndrome (LQTS), Brugada syndrome (BrS) and dilative cardiomyopathy (DCM), which may predispose to fatal arrhythmias and sudden death. We identified the heterozygous variant c.316A > G, p.(Ser106Gly) in a 35-year-old patient with survived cardiac arrest. In the present study, we aimed to investigate the functional impact of the variant to clarify the medical relevance. Methods Mutant as well as wild type GFP tagged Nav1.5 channels were expressed in HEK293 cells. We performed functional characterization experiments using patch-clamp technique. Results Electrophysiological measurements indicated, that the detected missense variant alters Nav1.5 channel functionality leading to a gain-of-function effect. Cells expressing S106G channels show an increase in Nav1.5 current over the entire voltage window. Conclusion The results support the assumption that the detected sequence aberration alters Nav1.5 channel function and may predispose to cardiac arrhythmias and sudden cardiac death.

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