Glutamate is an example of an excitatory amino acid neurotransmitter that acts v

Question

Glutamate is an example of an excitatory amino acid neurotransmitter that acts via direct synaptic transmission when it is released from presynaptic neurons in the brain. Based on the background information, which of the following statements is INCORRECT regarding the exocytotic release of glutamate from the presynaptic neuron? Exocytosis occurs by fusion of the membranes of the synaptic vesicles and the neuronal cell membrane Glutamate is stored in the terminal of the presynaptic neuron in synaptic vesicles In the absence of an action potential, Ca^2+ ions have a concentration gradient across the neuronal membrane with a 10,000-fold greater concentration extracellularly compared with intracellularly Exocytosis is stimulated by an influx of Ca^2+ ions when the action potential reaches the synaptic terminal Ca^2+ ions enter the presynaptic neuron due to the opening of ligand-gated calcium channels

Explanation / Answer

The answer is option E. All the statements regarding exocytosis of glutamate are correct except E. Ca2+ ions enter the presynaptic neuron due to the opening of voltage gated calcium channel. Ligand gated calcium ion channel opens in postsynaptic neuron. Both play role in exocytosis of glutamate but the difference is:

Voltage-gated calcium channel opens in presynaptic neuron

Ligand-gated calcium channel opens in postsynaptic neuron

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