Module 10: Figure mossy fibre presynaptic Ca2+ release
Spontaneous transmitter release from a mossy fibre bouton triggered by a Ca2+ spark.
The working hypothesis shown in this figure suggests that activation of the nicotinic acetylcholine receptor (nAChR) introduces Ca2+ into the bouton that begins to load the endoplasmic reticulum (ER). When the ER becomes overloaded, the ryanodine receptors (RYRs) become sensitized and begin to release spontaneous Ca2+ sparks that trigger transmitter release. (The information and ideas for this figure were taken from Sharma and Vijayaraghavan 2003.)