voltage-gated calcium channel activity involved in positive regulation of presynaptic cytosolic calcium levels

Definition

Target type: molecularfunction

Positive regulation of presynaptic cytosolic calcium ion concentrations via the directed movement of calcium ions across the plasma-membrane into the cytosol via the action of voltage-gated calcium ion channels. This is the first step in synaptic transmission. [GOC:dos]

Voltage-gated calcium channels (VGCCs) are transmembrane proteins that open in response to changes in membrane potential, specifically depolarization. When activated, they allow the influx of calcium ions (Ca2+) into the cell. In the context of presynaptic neurons, these channels play a crucial role in neurotransmitter release.

Upon arrival of an action potential at the presynaptic terminal, depolarization of the membrane opens VGCCs. The influx of Ca2+ triggers a cascade of events that lead to the fusion of synaptic vesicles containing neurotransmitters with the presynaptic membrane, resulting in neurotransmitter release into the synaptic cleft.

Positive regulation of presynaptic cytosolic calcium levels by VGCC activity is essential for proper neurotransmission. Increased Ca2+ influx through VGCCs enhances the probability of vesicle fusion and neurotransmitter release. This regulation can occur through several mechanisms, including:

1. **Increased channel opening probability:** Factors like membrane depolarization, neurotransmitter release, and second messenger signaling can enhance the likelihood of VGCC opening, leading to greater Ca2+ influx.
2. **Increased channel conductance:** Some modulators can increase the permeability of the channel, allowing for a greater influx of Ca2+ per unit time.
3. **Increased channel density:** Neuronal activity can induce the expression of more VGCCs at the presynaptic terminal, thereby increasing the overall Ca2+ influx capacity.

Disruption of this positive regulation, either through impaired VGCC function or alterations in their expression, can lead to deficits in neurotransmission, contributing to neurological disorders. This highlights the critical role of VGCC activity in regulating presynaptic Ca2+ levels and ensuring efficient communication between neurons.'
"

Proteins (1)

Compounds (2)