synaptic vesicle cycle

Definition

Target type: biologicalprocess

A biological process in which synaptic vesicles are loaded with neurotransmitters, move to the active zone, exocytose and are then recycled via endocytosis, ultimately leading to reloading with neurotransmitters. [GOC:aruk, GOC:bc, PMID:15217342]

The synaptic vesicle cycle is a fundamental process in neuronal communication, enabling the rapid and precise release of neurotransmitters at synapses. It involves a series of intricate steps that ensure efficient and regulated neurotransmission.

**1. Vesicle Formation and Filling:**

* Synaptic vesicles are small membrane-bound organelles that store neurotransmitters.
* They are formed by budding from the plasma membrane or by recycling of existing vesicles.
* As they form, they are filled with neurotransmitters through specific transporter proteins.

**2. Docking and Priming:**

* Once filled, vesicles are transported to the presynaptic terminal, where they dock with the plasma membrane at specialized sites called active zones.
* Docking involves interactions between vesicle proteins and proteins on the plasma membrane.
* During priming, vesicles undergo further molecular rearrangements to become competent for fusion.

**3. Exocytosis (Neurotransmitter Release):**

* Upon arrival of an action potential at the presynaptic terminal, voltage-gated calcium channels open.
* Calcium influx triggers a cascade of events that lead to vesicle fusion with the plasma membrane.
* This fusion releases neurotransmitters into the synaptic cleft, the space between the presynaptic and postsynaptic neurons.

**4. Endocytosis (Vesicle Retrieval):**

* After neurotransmitter release, the vesicle membrane is retrieved from the plasma membrane through a process called endocytosis.
* This involves the formation of clathrin-coated pits, which pinch off to form new vesicles.
* Endocytosis ensures the recycling of vesicle membrane and allows for the replenishment of the vesicle pool.

**5. Vesicle Recycling and Refilling:**

* Newly formed vesicles are transported back to the presynaptic terminal.
* They are refilled with neurotransmitters and become available for subsequent rounds of exocytosis.

**6. Regulation and Control:**

* The synaptic vesicle cycle is tightly regulated by various proteins, including SNAREs, synaptotagmin, and calcium sensors.
* These proteins ensure efficient and precise neurotransmitter release in response to neuronal activity.

The synaptic vesicle cycle is essential for maintaining neuronal communication. It ensures that neurotransmitters are released in a controlled and regulated manner, allowing for precise and efficient signaling between neurons.'
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Proteins (1)

Compounds (76)