|Jmol-3D images||Image 1|
|Molar mass||493.547 g/mol|
(what is: / ?)|
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Ryanodine is a poisonous alkaloid found in the South American plant Ryania speciosa (Flacourtiaceae). It was originally used as an insecticide.
The compound has extremely high affinity to the open-form ryanodine receptor, a group of calcium channels found in skeletal muscle, smooth muscle, and heart muscle cells. It binds with such high affinity to the receptor that it was used as a label for the first purification of that class of ion channels and gave its name to it.
At nanomolar concentrations, ryanodine locks the receptor in a half-open state, whereas it fully closes them at micromolar concentration. The effect of the nanomolar-level binding is that ryanodine causes release of calcium from calcium stores as the sarcoplasmic reticulum in the cytoplasm, leading to massive muscular contractions. The effect of micromolar-level binding is paralysis. This is true for both mammals and insects.