Imperatoxin A (IpTxa) from Pandinus imperator stimulates [3H]ryanodine binding to RyR3 channels

FEBS Letters

Valdivia, Hector H.¹  Simeoni, Ilenia²  Sorrentino, Vincenzo²  Zhu, Xinsheng¹  Garcı́a, Jesus³  Rossi, Daniela² 

[1] Department of Physiology, University of Wisconsin, Medical School, Madison, WI 53706, USA;Molecular Medicine Section, Department of Neuroscience, University of Siena, via Aldo Moro 5, 53100 Siena, Italy;Department of Physiology and Biophysics, University of Illinois at Chicago College of Medicine, Chicago, IL, USA

关键词: Sarcoplasmic reticulum;    Excitation contraction coupling;    Ryanodine receptor;    Calcium release channel;    Toxin;   

DOI  :  10.1016/S0014-5793(01)03013-7

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The effect of imperatoxin A (IpTx_a) on the ryanodine receptor type 3 (RyR3) was studied. IpTx_a stimulates [³H]ryanodine binding to RyR3-containing microsomes, but this effect requires toxin concentrations higher than those required to stimulate RyR1 channels. The effect of IpTx_a on RyR3 channels was observed at calcium concentrations in the range 0.1 μM to 10 mM. By contrast, RyR2 channels were not significantly affected by IpTx_a in the same calcium ranges. Single channel current measurements indicated that IpTx_a induced subconductance state in RyR3 channels that was similar to those observed with RyR1 and RyR2 channels. These results indicate that IpTx_a is capable of inducing similar subconductance states in all three RyR isoforms, while stimulation of [³H]ryanodine binding by this toxin results in isoform-specific responses, with RyR1 being the most sensitive channel, RyR3 displaying an intermediate response and RyR2 the least responsive ones.

【 授权许可】

Unknown