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Determining Ca 2+ ‐sensor binding time and its variability in evoked neurotransmitter release
Author(s) -
Yoon Ava Chomee,
Kathpalia Vinnie,
D'Silva Sahana,
Cimenser Aylin,
Hua ShaoYing
Publication year - 2008
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2007.130740
Subject(s) - neurotransmission , neurotransmitter , biophysics , chemistry , extracellular , neuromuscular transmission , crayfish , synaptic cleft , neuroscience , central nervous system , biology , biochemistry , receptor , endocrinology , fishery
The speed and reliability of neuronal reactions are important factors for proper functioning of the nervous system. To understand how organisms use protein molecules to carry out very fast biological actions, we quantified single‐molecule reaction time and its variability in synaptic transmission. From the synaptic delay of crayfish neuromuscular synapses the time for a few Ca 2+ ions to bind with their sensors in evoked neurotransmitter release was estimated. In standard crayfish saline at room temperature, the average Ca 2+ binding time was 0.12 ms for the first evoked quanta. At elevated extracellular Ca 2+ concentrations this binding time reached a limit due to saturation of Ca 2+ influx. Analysis of the synaptic delay variance at various Ca 2+ concentrations revealed that the variability of the Ca 2+ ‐sensor binding time is the major source of the temporal variability of synaptic transmission, and that the Ca 2+ ‐independent molecular reactions after Ca 2+ influx were less stochastic. The results provide insights into how organisms maximize reaction speed and reliability.